runelite-client: Preload certain slow classes

runelite-client/src/main/java/net/runelite/client/ClassPreloader.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2019 Abex
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.runelite.client;
+
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
+import net.runelite.client.ui.FontManager;
+
+/**
+ * Loads some slow to initialize classes (hopefully) before they are needed to streamline client startup
+ */
+@SuppressWarnings({"ResultOfMethodCallIgnored", "unused"})
+class ClassPreloader
+{
+	static void preload()
+	{
+		// This needs to enumerate the system fonts for some reason, and that takes a while
+		FontManager.getRunescapeSmallFont();
+
+		// This needs to load a timezone database that is mildly large
+		ZoneId.of("Europe/London");
+
+		// This just needs to call 20 different DateTimeFormatter constructors, which are slow
+		Object unused = DateTimeFormatter.BASIC_ISO_DATE;
+	}
+}

runelite-client/src/main/java/net/runelite/client/RuneLite.java

@@ -204,6 +204,7 @@ public class RuneLite
 		new Thread(() ->
 		{
 			clientLoader.get();
+			ClassPreloader.preload();
 		}, "Preloader").start();
 
 		final boolean developerMode = options.has("developer-mode") && RuneLiteProperties.getLauncherVersion() == null;