Avoid re-creating title version string every frame (#2117)

* Avoid re-creating title version string every frame

* Marked title version string that it has been changed by Dalamud by
  appending a newline payload with a string expression embedded within,
  which the game will ignore (effectively `<br(!Dalamud!)>`.)
* Added `PluginManager.LoadedPluginCount` which will count the number of
  loaded plugin without making a copy of the plugin list.
* Made TitleScreenMenuWindow.OnVersionStringDraw` update the title
  version text addon only if number of loaded plugin changes or the text
  is missing the custom suffix from the first point.

* Use OriginalTextPointer to determine if SetText(ROS) has been called

Dalamud/Interface/Internal/Windows/TitleScreenMenuWindow.cs

@@ -10,7 +10,6 @@ using Dalamud.Game.Addon.Lifecycle.AddonArgTypes;
 using Dalamud.Game.ClientState;
 using Dalamud.Game.Gui;
 using Dalamud.Game.Text;
-using Dalamud.Game.Text.SeStringHandling;
 using Dalamud.Interface.Animation.EasingFunctions;
 using Dalamud.Interface.ManagedFontAtlas;
 using Dalamud.Interface.ManagedFontAtlas.Internals;
@@ -19,16 +18,18 @@ using Dalamud.Interface.Utility;
 using Dalamud.Interface.Utility.Raii;
 using Dalamud.Interface.Windowing;
 using Dalamud.Plugin.Internal;
-using Dalamud.Plugin.Internal.Types;
 using Dalamud.Plugin.Services;
 using Dalamud.Storage.Assets;
-using Dalamud.Support;
 using Dalamud.Utility;
 
 using FFXIVClientStructs.FFXIV.Component.GUI;
 
 using ImGuiNET;
 
+using Lumina.Text.ReadOnly;
+
+using LSeStringBuilder = Lumina.Text.SeStringBuilder;
+
 namespace Dalamud.Interface.Internal.Windows;
 
 /// <summary>
@@ -59,6 +60,8 @@ internal class TitleScreenMenuWindow : Window, IDisposable
     private InOutCubic? fadeOutEasing;
 
     private State state = State.Hide;
+
+    private int lastLoadedPluginCount = -1;
     
     /// <summary>
     /// Initializes a new instance of the <see cref="TitleScreenMenuWindow"/> class.
@@ -441,29 +444,37 @@ internal class TitleScreenMenuWindow : Window, IDisposable
         textNode->TextFlags |= (byte)TextFlags.MultiLine;
         textNode->AlignmentType = AlignmentType.TopLeft;
 
+        var containsDalamudVersionString = textNode->OriginalTextPointer == textNode->NodeText.StringPtr;
         if (!this.configuration.ShowTsm || !this.showTsm.Value)
         {
-            textNode->NodeText.SetString(addon->AtkValues[1].String);
+            if (containsDalamudVersionString)
+                textNode->SetText(addon->AtkValues[1].String);
+            this.lastLoadedPluginCount = -1;
             return;
         }
 
         var pm = Service<PluginManager>.GetNullable();
+        var count = pm?.LoadedPluginCount ?? 0;
 
-        var pluginCount = pm?.InstalledPlugins.Count(c => c.State == PluginState.Loaded) ?? 0;
+        // Avoid rebuilding the string every frame.
+        if (containsDalamudVersionString && count == this.lastLoadedPluginCount)
+            return;
+        this.lastLoadedPluginCount = count;
 
-        var titleVersionText = new SeStringBuilder()
-                               .AddText(addon->AtkValues[1].GetValueAsString())
-                               .AddText("\n\n")
-                               .AddUiGlow(701)
-                               .AddUiForeground(SeIconChar.BoxedLetterD.ToIconString(), 539)
-                               .AddUiGlowOff()
-                               .AddText($" Dalamud: {Util.GetScmVersion()}")
-                               .AddText($" - {pluginCount} {(pluginCount != 1 ? "plugins" : "plugin")} loaded");
+        var lssb = LSeStringBuilder.SharedPool.Get();
+        lssb.Append(new ReadOnlySeStringSpan(addon->AtkValues[1].String)).Append("\n\n");
+        lssb.PushEdgeColorType(701).PushColorType(539)
+            .Append(SeIconChar.BoxedLetterD.ToIconChar())
+            .PopColorType().PopEdgeColorType();
+        lssb.Append($" Dalamud: {Util.GetScmVersion()}");
 
-        if (pm?.SafeMode ?? false) 
-            titleVersionText.AddUiForeground(" [SAFE MODE]", 17);
+        lssb.Append($" - {count} {(count != 1 ? "plugins" : "plugin")} loaded");
 
-        textNode->NodeText.SetString(titleVersionText.Build().EncodeWithNullTerminator());
+        if (pm?.SafeMode is true)
+            lssb.PushColorType(17).Append(" [SAFE MODE]").PopColorType();
+
+        textNode->SetText(lssb.GetViewAsSpan());
+        LSeStringBuilder.SharedPool.Return(lssb);
     }
 
     private void TitleScreenMenuEntryListChange() => this.privateAtlas.BuildFontsAsync();

Dalamud/Plugin/Internal/PluginManager.cs

@@ -162,6 +162,27 @@ internal class PluginManager : IInternalDisposableService
     /// </summary>
     public static int DalamudApiLevel { get; private set; }
 
+    /// <summary>
+    /// Gets the number of loaded plugins.
+    /// </summary>
+    public int LoadedPluginCount
+    {
+        get
+        {
+            var res = 0;
+            lock (this.pluginListLock)
+            {
+                foreach (var p in this.installedPluginsList)
+                {
+                    if (p.State == PluginState.Loaded)
+                        res++;
+                }
+            }
+
+            return res;
+        }
+    }
+
     /// <summary>
     /// Gets a copy of the list of all loaded plugins.
     /// </summary>