#2010 Draw the Spell Cache editor on first open, not at addon load

SpellCache.lua's setup ended with SelectTab on the first cache tab, which
fires GUIDrawSpellCacheEditor and builds two EditBoxes plus labels for
EVERY cached spell -- at load time, for a frame that starts hidden. The
cache only grows (imports merge the exporter's whole cache, the
translator caches every name it resolves, nothing prunes), so long-time
users paid seconds of frozen client inside the on-demand
LoadAddOn("GSE_GUI") that opening any first GSE window triggers.
Measured: 3.8s of a 4.4s blocked frame.

Defer the initial tab draw to the frame's first OnShow: the window pays
its own cost when actually opened, and loading the GUI stops stalling
the client.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: LarryThiessen

GSE_GUI/SpellCache.lua

@@ -229,9 +229,22 @@ tabgrp:SetCallback(
 tabgrp:SetFullWidth(true)
 tabgrp:SetFullHeight(true)
 
-if cacheTabs[1] then
-    tabgrp:SelectTab(cacheTabs[1].value)
-end
+-- Draw the tab's contents when the window is first SHOWN, not while the addon
+-- loads. SelectTab fires GUISelectCacheTab -> GUIDrawSpellCacheEditor, which
+-- builds two EditBoxes plus labels for EVERY cached spell. This frame starts
+-- hidden and most authors never open it, so doing that during the on-demand
+-- LoadAddOn (which is what opening the GSE menu triggers) stalled the client
+-- for seconds on a cache built up over years.
+local pendingInitialTab = cacheTabs[1] and cacheTabs[1].value
+cacheFrame.frame:HookScript(
+    "OnShow",
+    function()
+        if not pendingInitialTab then return end
+        local tab = pendingInitialTab
+        pendingInitialTab = nil
+        tabgrp:SelectTab(tab)
+    end
+)
 cacheFrame:AddChild(tabgrp)
 
 if cacheFrame and cacheFrame.frame and GSE.RegisterUIScaleFrame then