Im experiencing some very odd slowdown on both the 6600 and 6630. I've got what is essentially a top down tile based racing game. When the game starts the first few seconds of the race splutter and stutters about, and the framerate seems to slow right down. It looks like the game is essentially choking for a few seconds, then returns to normal. The odd thing is, the overall processing should be consistant no matter what, and there is no explainable extra overheads during this period of slowdown. I can even restart the same race, and it all fine the 2nd time I run it.
I've tried various tests, like removing the BG tile render, and also removing various other drawing aspects the game and the game still slows down. This leads me to think its not graphics related. But there is no obvious reason for this. I dont have any garbage collection in the main loop, as I know this really slows things down. However, there is the odd gc() after loads, so this should all be safe.
This only seems to be a problem on the 6600 and 6630. The same basic logic works fine on the 7650/3650 and other devices such as SE K700i etc...
Is there some known issues the 6600/6630 that can be causing these odd effect?
Thanks in advance for any help or pointers.