diff --git a/addons/scoreboard/damagedb.lua b/addons/scoreboard/damagedb.lua
index 4b22b615c9..f673f28286 100644
--- a/addons/scoreboard/damagedb.lua
+++ b/addons/scoreboard/damagedb.lua
@@ -3,7 +3,8 @@ local MergedPlayer = require 'mergedplayer'
 
 local DamageDB = {
     db = T{},
-    filter = T{}
+    filter = T{},
+    last_update = {}
 }
 
 --[[
@@ -79,11 +80,13 @@ function DamageDB:_get_player(mob, player_name)
     if not self.db[mob] then
         self.db[mob] = T{}
     end
-    
+
     if not self.db[mob][player_name] then
         self.db[mob][player_name] = Player:new{name = player_name}
     end
-    
+
+    self.last_update[mob] = os.time()
+
     return self.db[mob][player_name]
 end
 
@@ -128,6 +131,24 @@ end
 
 function DamageDB:reset()
     self.db = T{}
+    self.last_update = {}
+end
+
+
+-- Removes mob entries that haven't received data in max_age_seconds.
+-- Returns true if any mobs were pruned.
+function DamageDB:prune(max_age_seconds)
+    local now = os.time()
+    local pruned = false
+    for mob, _ in pairs(self.db) do
+        local ts = self.last_update[mob]
+        if ts and (now - ts) > max_age_seconds then
+            self.db[mob] = nil
+            self.last_update[mob] = nil
+            pruned = true
+        end
+    end
+    return pruned
 end
 
 
diff --git a/addons/scoreboard/data/settings.xml b/addons/scoreboard/data/settings.xml
index 2478be1120..5f380212a9 100644
--- a/addons/scoreboard/data/settings.xml
+++ b/addons/scoreboard/data/settings.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0" ?>
 <settings>
-  <!--
+	<!--
 	This file controls the settings for the Scoreboard plugin.
 	Settings in the <global> section apply to all characters
 
@@ -9,6 +9,7 @@
 		posY - y coordinate for position
 		numPlayers - The maximum number of players to display damage for
 		bgTransparency - Transparency level for the background. 0-255 range
+		logPeriod - Minutes to keep mob entries before pruning (0 = keep forever)
 	-->
 	<global>
 		<posX>10</posX>
@@ -16,6 +17,7 @@
 		<bgTransparency>200</bgTransparency>
 		<numPlayers>8</numPlayers>
         <UpdateFrequency>0.5</UpdateFrequency>
+		<logPeriod>0</logPeriod>
 	</global>
 
 	<!--
diff --git a/addons/scoreboard/mergedplayer.lua b/addons/scoreboard/mergedplayer.lua
index 8346cfd15e..8a4ae5cded 100644
--- a/addons/scoreboard/mergedplayer.lua
+++ b/addons/scoreboard/mergedplayer.lua
@@ -209,24 +209,12 @@ end
 function MergedPlayer:wsavg()
     local wsdmg   = 0
     local wscount = 0
-    --[[
-    for _, p in pairs(self.players) do
-        for _, dmgtable in pairs(p.ws) do
-            for _, dmg in pairs(dmgtable) do
-                wsdmg = wsdmg + dmg
-                wscount = wscount + 1
-            end
-        end 
-    end
-    ]]
-    
+
     for _, p in pairs(self.players) do
-        for _, dmg in pairs(p.ws) do
-            wsdmg = wsdmg + dmg
-            wscount = wscount + 1
-        end
+        wsdmg   = wsdmg + p.ws_total
+        wscount = wscount + p.ws_count
     end
-    
+
     if wscount > 0 then
         return {wsdmg / wscount, wscount}
     else
@@ -236,12 +224,12 @@ end
 
 function MergedPlayer:wsacc()
     local hits, misses = 0, 0
-    
+
     for _, p in ipairs(self.players) do
-        hits = hits + table.length(p.ws)
+        hits = hits + p.ws_count
         misses = misses + p.ws_misses
     end
-    
+
     local total = hits + misses
     if total > 0 then
         return {hits / total, total}
@@ -254,16 +242,9 @@ end
 function MergedPlayer:merge(other)
     self.damage = self.damage + other.damage
 
-    for ws_id, values in pairs(other.ws) do
-        if self.ws[ws_id] then
-            for _, value in ipairs(values) do
-                self.ws[ws_id]:append(value)
-            end
-        else
-            self.ws[ws_id] = table.copy(values)
-        end
-    end
-    
+    self.ws_total = self.ws_total + other.ws_total
+    self.ws_count = self.ws_count + other.ws_count
+
     self.m_hits   = self.m_hits + other.m_hits
     self.m_misses = self.m_misses + other.m_misses
     self.m_min    = math.min(self.m_min, other.m_min)
diff --git a/addons/scoreboard/player.lua b/addons/scoreboard/player.lua
index e333c2fd9c..e524c2a571 100644
--- a/addons/scoreboard/player.lua
+++ b/addons/scoreboard/player.lua
@@ -16,7 +16,8 @@ function Player:new (o)
     local attrs = {
         clock = nil,            -- specific DPS clock for this player
         damage = 0,             -- total damage done by this player
-        ws  = T{},              -- table of all WS and their corresponding damage
+        ws_total = 0,           -- sum of all WS damage
+        ws_count = 0,           -- number of WS landed
         ws_misses = 0,          -- total ws misses
         m_hits = 0,             -- total melee hits
         m_misses = 0,           -- total melee misses
@@ -67,14 +68,8 @@ end
 
 
 function Player:add_ws_damage(ws_name, damage)
-    --[[
-    if not self.ws[ws_name] then
-        self.ws[ws_name] = L{}
-    end
-    
-    self.ws[ws_name]:append(damage)
-    ]]
-    self.ws:append(damage)
+    self.ws_count = self.ws_count + 1
+    self.ws_total = self.ws_total + damage
     self.damage = self.damage + damage
 end
 
diff --git a/addons/scoreboard/readme.txt b/addons/scoreboard/readme.txt
index 1e5ff456cf..e390481570 100644
--- a/addons/scoreboard/readme.txt
+++ b/addons/scoreboard/readme.txt
@@ -84,6 +84,13 @@ Command list:
   //sb stat acc            Shows accuracy for everyone
   //sb stat crit Flippant  Only show crit rate for Flippant
 
+* SET <flag> <value>
+  Sets a configuration variable in-game and saves it to settings.xml.
+  Run //sb help for the full list of valid flags.
+  Examples:
+  //sb set LogPeriod 30    Prune mob entries after 30 minutes of inactivity
+  //sb set LogPeriod 0     Disable pruning (keep mob entries forever)
+
 The settings file, located in addons/scoreboard/data/settings.xml, contains
 additional configuration options:
 * posX - x coordinate for position
@@ -99,7 +106,9 @@ additional configuration options:
 * showallidps - Set to true to display the alliance DPS, false otherwise.
 * resetfilters - Set to true if you want filters reset when you "//sb reset", false otherwise.
 * showfellow - Set to true to display your adventuring fellow's DPS, false otherwise.
- 
+* logPeriod - Minutes to keep mob entries before pruning (0 = keep forever).
+              Can also be changed in-game with //sb set LogPeriod <minutes>.
+
 Caveats:
 * DPS is an approximation, although I tested it manually and found it to
   be very accurate. Because DPS accumulation is based on the game's notion
diff --git a/addons/scoreboard/scoreboard.lua b/addons/scoreboard/scoreboard.lua
index 76ba9b5e58..72766a9771 100644
--- a/addons/scoreboard/scoreboard.lua
+++ b/addons/scoreboard/scoreboard.lua
@@ -20,6 +20,25 @@ dps_db    = require('damagedb'):new() -- global for now
 
 -------------------------------------------------------
 
+-- Message ID lookup tables (allocated once at load, O(1) membership test)
+local ranged_hit_ids = {[157]=true, [352]=true, [576]=true, [577]=true}
+local skillchain_ids = {
+    [196]=true,[223]=true,[288]=true,[289]=true,[290]=true,[291]=true,[292]=true,
+    [293]=true,[294]=true,[295]=true,[296]=true,[297]=true,[298]=true,[299]=true,
+    [300]=true,[301]=true,[302]=true,[385]=true,[386]=true,[387]=true,[388]=true,
+    [389]=true,[390]=true,[391]=true,[392]=true,[393]=true,[394]=true,[395]=true,
+    [396]=true,[397]=true,[398]=true,[732]=true,[767]=true,[768]=true,[769]=true,[770]=true
+}
+
+local function tbl_contains(t, val)
+    for _, v in pairs(t) do
+        if v == val then return true end
+    end
+    return false
+end
+
+local display_dirty = false
+
 -- Conventional settings layout
 local default_settings = {}
 default_settings.numplayers = 8
@@ -33,6 +52,7 @@ default_settings.combinepets = true
 default_settings.oneperline = false
 default_settings.compactsc = false
 default_settings.creditpetdamagetoowner = false
+default_settings.logperiod = 0
 
 default_settings.display = {}
 default_settings.display.pos = {}
@@ -98,7 +118,7 @@ windower.register_event('addon command', function()
             sb_output('sb stat <stat> [<player>] : Shows specific damage stats. Respects filters. If player isn\'t specified, stats for everyone are displayed.')
             sb_output('  Valid stats are: '..dps_db.player_stat_fields:tostring():stripchars('{}"'))
             sb_output('sb set <flag> <value> : Sets configuration variables')
-            sb_output('  Valid flags are: CombinePets, NumPlayers, BGTransparency, Font, SBColor, ShowAlliDPS, ResetFilters, ShowFellow, OnePerLine, CompactSC, CreditPetDamageToOwner')
+            sb_output('  Valid flags are: CombinePets, NumPlayers, BGTransparency, Font, SBColor, ShowAlliDPS, ResetFilters, ShowFellow, OnePerLine, CompactSC, CreditPetDamageToOwner, LogPeriod')
         elseif command == 'pos' then
             if params[2] then
                 local posx, posy = tonumber(params[1]), tonumber(params[2])
@@ -209,6 +229,19 @@ windower.register_event('addon command', function()
                 end
                 settings:save()
                 sb_output("Setting 'CreditPetDamageToOwner' set to " .. tostring(settings.creditpetdamagetoowner))
+            elseif setting:lower() == 'logperiod' then
+                local val = tonumber(params[2])
+                if not val or val < 0 then
+                    error("Invalid value for 'LogPeriod'. Must be a number >= 0 (minutes, 0 = disabled).")
+                    return
+                end
+                settings.logperiod = val
+                settings:save()
+                if val == 0 then
+                    sb_output("Setting 'LogPeriod' disabled (mob entries kept forever)")
+                else
+                    sb_output("Setting 'LogPeriod' set to " .. val .. " minute(s)")
+                end
             end
         elseif command == 'reset' then
             reset()
@@ -383,26 +416,41 @@ local function update_dps_clock()
             end
         end
     end
+
+    local was_active = dps_clock:is_active()
     if player and (player.in_combat or (pet ~= nil and pet.status == 1)) then
         dps_clock:advance()
     else
         dps_clock:pause()
     end
 
-    display:update()
+    if settings.logperiod > 0 then
+        if dps_db:prune(settings.logperiod * 60) then
+            display_dirty = true
+        end
+    end
+
+    if dps_clock:is_active() or display_dirty or was_active ~= dps_clock:is_active() then
+        display:update()
+        display_dirty = false
+    end
 end
 
 
--- Returns all mob IDs for anyone in your alliance, including their pets.
-function get_ally_mob_ids()
-    local allies = T{}
+-- Builds a set of all mob IDs for anyone in your alliance, including their pets.
+-- Returns a plain table with [id]=true entries for O(1) lookup.
+function build_ally_set()
+    local allies = {}
     local party = windower.ffxi.get_party()
 
     for _, member in pairs(party) do
         if type(member) == 'table' and member.mob then
-            allies:append(member.mob.id)
-            if member.mob.pet_index and member.mob.pet_index> 0 and windower.ffxi.get_mob_by_index(member.mob.pet_index) then
-                allies:append(windower.ffxi.get_mob_by_index(member.mob.pet_index).id)
+            allies[member.mob.id] = true
+            if member.mob.pet_index and member.mob.pet_index > 0 then
+                local pet_mob = windower.ffxi.get_mob_by_index(member.mob.pet_index)
+                if pet_mob then
+                    allies[pet_mob.id] = true
+                end
             end
         end
     end
@@ -410,109 +458,110 @@ function get_ally_mob_ids()
     if settings.showfellow then
         local fellow = windower.ffxi.get_mob_by_target("ft")
         if fellow ~= nil then
-            allies:append(fellow.id)
+            allies[fellow.id] = true
         end
     end
-    
-    return allies
-end
-
 
--- Returns true if is someone (or a pet of someone) in your alliance.
-function mob_is_ally(mob_id)
-    -- get zone-local ids of all allies and their pets
-    return get_ally_mob_ids():contains(mob_id)
+    return allies
 end
 
 
 function action_handler(raw_actionpacket)
     local actionpacket = ActionPacket.new(raw_actionpacket)
-    
-    local category = actionpacket:get_category_string()
 
     local player = windower.ffxi.get_player()
+    if not player then
+        return
+    end
+
     local pet
-    if player ~= nil then
-        local player_mob = windower.ffxi.get_mob_by_id(player.id)
-        if player_mob ~= nil then
-            local pet_index = player_mob.pet_index
-            if pet_index ~= nil then
-                pet = windower.ffxi.get_mob_by_index(pet_index)
-            end
+    local player_mob = windower.ffxi.get_mob_by_id(player.id)
+    if player_mob ~= nil then
+        local pet_index = player_mob.pet_index
+        if pet_index ~= nil then
+            pet = windower.ffxi.get_mob_by_index(pet_index)
         end
     end
-    if not player or not (windower.ffxi.get_player().in_combat or (pet ~= nil and pet.status == 1)) then
-        -- nothing to do
+
+    if not (player.in_combat or (pet ~= nil and pet.status == 1)) then
         return
     end
-    
+
+    display_dirty = true
+
+    local allies = build_ally_set()
+    local actor_is_ally = allies[actionpacket.raw.actor_id] or false
+    local actor_name
+
     for target in actionpacket:get_targets() do
-        for subactionpacket in target:get_actions() do
-            if (mob_is_ally(actionpacket.raw.actor_id) and not mob_is_ally(target.raw.id)) then
-                -- Ignore actions within the alliance, but parse all alliance-outwards or outwards-alliance packets.
+        local target_is_ally = allies[target.raw.id] or false
+
+        if actor_is_ally and not target_is_ally then
+            if not actor_name then
+                actor_name = create_mob_name(actionpacket)
+            end
+            local target_name = target:get_name()
+
+            for subactionpacket in target:get_actions() do
                 local main  = subactionpacket:get_basic_info()
                 local add   = subactionpacket:get_add_effect()
                 local spike = subactionpacket:get_spike_effect()
-                if main.message_id == 1 then
-                    dps_db:add_m_hit(target:get_name(), create_mob_name(actionpacket), main.param)
-                elseif main.message_id == 67 then
-                    dps_db:add_m_crit(target:get_name(), create_mob_name(actionpacket), main.param)
-                elseif main.message_id == 15 or main.message_id == 63 then
-                    dps_db:incr_misses(target:get_name(), create_mob_name(actionpacket))
-                elseif main.message_id == 353 then
-                    dps_db:add_r_crit(target:get_name(), create_mob_name(actionpacket), main.param)
-                elseif T{157, 352, 576, 577}:contains(main.message_id) then
-                    dps_db:add_r_hit(target:get_name(), create_mob_name(actionpacket), main.param)
-                elseif main.message_id == 353 then
-                    dps_db:add_r_crit(target:get_name(), create_mob_name(actionpacket), main.param)
-                elseif main.message_id == 354 then
-                    dps_db:incr_r_misses(target:get_name(), create_mob_name(actionpacket))
-                elseif main.message_id == 188 then
-                    dps_db:incr_ws_misses(target:get_name(), create_mob_name(actionpacket))
+                local msg = main.message_id
+
+                if msg == 1 then
+                    dps_db:add_m_hit(target_name, actor_name, main.param)
+                elseif msg == 67 then
+                    dps_db:add_m_crit(target_name, actor_name, main.param)
+                elseif msg == 15 or msg == 63 then
+                    dps_db:incr_misses(target_name, actor_name)
+                elseif msg == 353 then
+                    dps_db:add_r_crit(target_name, actor_name, main.param)
+                elseif ranged_hit_ids[msg] then
+                    dps_db:add_r_hit(target_name, actor_name, main.param)
+                elseif msg == 354 then
+                    dps_db:incr_r_misses(target_name, actor_name)
+                elseif msg == 188 then
+                    dps_db:incr_ws_misses(target_name, actor_name)
                 elseif main.resource and main.resource == 'weapon_skills' and main.conclusion then
-                    dps_db:add_ws_damage(target:get_name(), create_mob_name(actionpacket), main.param, main.spell_id)
-                -- Siren's Hysteric Assault does HP drain and falls under message_id 802
-                elseif main.message_id == 802 then
-                    dps_db:add_damage(target:get_name(), create_mob_name(actionpacket), main.param)
+                    dps_db:add_ws_damage(target_name, actor_name, main.param, main.spell_id)
+                elseif msg == 802 then
+                    dps_db:add_damage(target_name, actor_name, main.param)
                 elseif main.conclusion then
-                    if main.conclusion.subject == 'target' and T(main.conclusion.objects):contains('HP') and main.param ~= 0 then
-                        dps_db:add_damage(target:get_name(), create_mob_name(actionpacket), (main.conclusion.verb == 'gains' and -1 or 1)*main.param)
+                    if main.conclusion.subject == 'target' and tbl_contains(main.conclusion.objects, 'HP') and main.param ~= 0 then
+                        dps_db:add_damage(target_name, actor_name, (main.conclusion.verb == 'gains' and -1 or 1)*main.param)
                     end
                 end
-                
+
                 if add and add.conclusion then
-                    local actor_name = create_mob_name(actionpacket)
-                    if not settings.compactsc then
-                        if T{196,223,288,289,290,291,292,
-                            293,294,295,296,297,298,299,
-                            300,301,302,385,386,387,388,
-                            389,390,391,392,393,394,395,
-                            396,397,398,732,767,768,769,770}:contains(add.message_id) then
-                            actor_name = string.format("Skillchain (%s)", actor_name:sub(1, 3))
-                        end
-                    else
-                        if T{196,223,288,289,290,291,292,
-                            293,294,295,296,297,298,299,
-                            300,301,302,385,386,387,388,
-                            389,390,391,392,393,394,395,
-                            396,397,398,732,767,768,769,770}:contains(add.message_id) then
-                            actor_name = string.format("SC:%s", actor_name:sub(1, 13))
+                    local sc_name = actor_name
+                    if skillchain_ids[add.message_id] then
+                        if not settings.compactsc then
+                            sc_name = string.format("Skillchain (%s)", actor_name:sub(1, 3))
+                        else
+                            sc_name = string.format("SC:%s", actor_name:sub(1, 13))
                         end
                     end
-                    if add.conclusion.subject == 'target' and T(add.conclusion.objects):contains('HP') and add.param ~= 0 then
-                        dps_db:add_damage(target:get_name(), actor_name, (add.conclusion.verb == 'gains' and -1 or 1)*add.param)
+                    if add.conclusion.subject == 'target' and tbl_contains(add.conclusion.objects, 'HP') and add.param ~= 0 then
+                        dps_db:add_damage(target_name, sc_name, (add.conclusion.verb == 'gains' and -1 or 1)*add.param)
                     end
                 end
                 if spike and spike.conclusion then
-                    if spike.conclusion.subject == 'target' and T(spike.conclusion.objects):contains('HP') and spike.param ~= 0 then
-                        dps_db:add_damage(target:get_name(), create_mob_name(actionpacket), (spike.conclusion.verb == 'gains' and -1 or 1)*spike.param)
+                    if spike.conclusion.subject == 'target' and tbl_contains(spike.conclusion.objects, 'HP') and spike.param ~= 0 then
+                        dps_db:add_damage(target_name, actor_name, (spike.conclusion.verb == 'gains' and -1 or 1)*spike.param)
                     end
                 end
-            elseif (mob_is_ally(target.raw.id) and not mob_is_ally(actionpacket.raw.actor_id)) then
+            end
+        elseif target_is_ally and not actor_is_ally then
+            if not actor_name then
+                actor_name = create_mob_name(actionpacket)
+            end
+            local target_name = target:get_name()
+
+            for subactionpacket in target:get_actions() do
                 local spike = subactionpacket:get_spike_effect()
                 if spike and spike.conclusion then
-                    if spike.conclusion.subject == 'actor' and T(spike.conclusion.objects):contains('HP') and spike.param ~= 0 then
-                        dps_db:add_damage(create_mob_name(actionpacket), target:get_name(), (spike.conclusion.verb == 'loses' and 1 or -1)*spike.param)
+                    if spike.conclusion.subject == 'actor' and tbl_contains(spike.conclusion.objects, 'HP') and spike.param ~= 0 then
+                        dps_db:add_damage(actor_name, target_name, (spike.conclusion.verb == 'loses' and 1 or -1)*spike.param)
                     end
                 end
             end
@@ -564,6 +613,12 @@ config.register(settings, function(settings)
     display:visibility(display.visible and windower.ffxi.get_info().logged_in)
 end)
 
+windower.register_event('unload', function()
+    if ActionPacket.close_listener then
+        ActionPacket.close_listener(action_handler)
+    end
+end)
+
 
 --[[
 Copyright (c) 2013-2014, Jerry Hebert