ACA500 slowdown

[DonutKing]

I'm running an ACA500, with flash 0.99, on my Rev6a A500, which is totally stock apart from a 512KB trapdoor expansion.

I've noticed that a number of demos slow down a lot on certain effects.
They'll run at normal speed most of the time but when certain effects are running, it turns into a slide show.
The best example is 'spasmolytic' by spaceballs. Look at the effect at about 2:22 here

[ Show youtube player ]

That's normal speed. On mine with ACA500, it slows to a crawl and the music slows down as well. Once that particular effect ends the demo speeds up to normal again.

Another demo I've noticed with this behaviour is this Tetragon demo - http://www.pouet.net/prod.php?which=51842 - the whole demo chugs with the ACA500 installed, even disabled, but runs normal speed with it removed.


There's a few others I've noticed this in but those are the only two I can name at the moment.

I've fiddled with memory options in the ACA500 boot menu, I've tried the disable jumper on the ACA500 but nothing seems to work.

However, if I physically remove the ACA500, everything works fine. The demos all run at normal speed.
Obviously plugging and unplugging the fragile edge connector is not ideal so I'm hoping there is a way this could be resolved through software.