Set ROM launcher framerate to 30fps. There's no need for it to be

a full 60fps, and it reduces CPU usage up to 30% on some systems.

Changes.txt

@@ -45,6 +45,11 @@
     this bug has only ever occurred in Windows XP, but it's been there
     since Stella 4.1.
 
+  * When in 'ROM launcher mode', Stella now uses less CPU time.
+
+  * Added ROM properties for D.K. VCS homebrew ROM, thanks to Andreas
+    Dietrich.
+
   * For the Linux/UNIX port:
     - The settings directory now uses the XDG Base Directory Specification.
       In most cases, this means that your files will now be stored in
@@ -66,9 +71,6 @@
         cd ~/Library/Preferences
         mv net.sourceforge.Stella.plist Stella-emu.plist
 
-  * Added ROM properties for D.K. VCS homebrew ROM, thanks to Andreas
-    Dietrich.
-
   * Updated internal ROM properties database to ROM-Hunter version 12
     (thanks go to RomHunter for his tireless research in this area).
     Related to this, updated the snapshot collection.

src/emucore/OSystem.cxx

@@ -425,7 +425,7 @@ bool OSystem::createLauncher(const string& startdir)
     myLauncher->reStack();
     myFrameBuffer->setCursorState();
 
-    setFramerate(60);
+    setFramerate(30);
     resetLoopTiming();
     status = true;
   }