I would also investigate your video ram requirements, what spec is your system? I have a 64MB fx5200 in my power mac g5 and are finding it very difficult to get good results once I start using a few big textures, if your front end is "resource rich" you might want to try disabling it to see if things don't improve with these hiccups.
Too much debug output is also something you should try and avoid.
Too much debug output is also something you should try and avoid.