Well I started the Amiga 500 quickstart mode (without any disks), the PC freezed on me when I closed Amiga. (I left the PC there like maybe for 10 minutes - the CPU was up at 89%).
I let the Amiga 1200 quickstart on but only for some less minutes. CPU was up at 100%.
If I enable Vsync, the game Dyna Blaster has the normal CPU % but the Sound % is way up since the beginning.
With other games, in general it seems to me that Vsync enabled does help a bit. But it still goes, now only just a bit later, again wacko.
I Have Windows XP; as for the driver version, etc. I would have still to need to check what I have.
@_Steve_: Seems like we have more or less a similar problem. But my main problem here is the sound while yours seems to be the graphics. I might have a minor slowdown on the graphics side but I didnt notice it. I was all the time busy beeing frustrated at the sound.