defer font texture releases by 250ms

evicted glyph textures may still be referenced by the current frame's
queued gui draws, so release them only after the frame has flushed

src/main/java/cc/fros/util/render/FrosFont.java

@@ -23,6 +23,7 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
@@ -53,11 +54,16 @@ public final class FrosFont {
         @Override
         protected boolean removeEldestEntry(Map.Entry<Key, Glyph> eldest) {
             if (size() <= MAX_CACHE) return false;
-            mc.getTextureManager().release(eldest.getValue().id());
+            queueRelease(eldest.getValue().id());
             return true;
         }
     };
 
+    // textures still referenced by this frame's queued draws are only
+    // released a moment later, once the frame has been flushed
+    private static final List<Identifier> PENDING_RELEASE = new ArrayList<>();
+    private static long lastQueuedAt;
+
     private record Key(int color, String text) {
     }
 
@@ -204,14 +210,29 @@ public final class FrosFont {
 
     private static void clearGlyphs() {
         for (Glyph glyph : new ArrayList<>(GLYPHS.values())) {
-            mc.getTextureManager().release(glyph.id());
+            queueRelease(glyph.id());
         }
         GLYPHS.clear();
     }
 
+    private static void queueRelease(Identifier id) {
+        lastQueuedAt = System.currentTimeMillis();
+        PENDING_RELEASE.add(id);
+    }
+
+    private static void flushReleases() {
+        if (PENDING_RELEASE.isEmpty()) return;
+        if (System.currentTimeMillis() - lastQueuedAt < 250) return;
+        for (Identifier id : PENDING_RELEASE) {
+            mc.getTextureManager().release(id);
+        }
+        PENDING_RELEASE.clear();
+    }
+
     // --- rasterizing ---
 
     private static void drawGlyphs(GuiGraphics context, String text, int x, int y, int color) {
+        flushReleases();
         Key key = new Key(color, text);
         Glyph glyph = GLYPHS.get(key);
         if (glyph == null) {