I have now re-written most of Neo Thunder to get rid of the slowdown. Now I want to finish up. However there is an occasional "jerk" on all the sprites (up to once per second). There are no frame drops in the new version of the game (it always runs at 60fps now). This jerk was also in the original game so it's not something I have added at least

As a test I removed all the joystick control, all game logic and the sprites and then just had one small sprite moving backwards and forwards at the top of the screen. And the jerk was still there. I also removed the BIOS update function from the VBL interrupt routine (just in case) and that made no difference

I have also disabled my virus checker and that made no difference either!


My feeling currently is that this "jerk" is something to do with MAME and the fact that the Neo Geo updates at 59hz while my display updates at 60.01 hz. Do you think this is right?

I have played around with the display options (I am using MAMEUI32) but have no luck yet. The only thing that removed the jerk was to un-throttle the game. Which is cheating!

Can people suggest a fix for this? I want to make a video showing the before and after (the original Neo Thunder compared to my newer version) and it won't look good if there is still a jerk in the game movement

Even though I can code, I don't really know much about MAME, since I rarely use it outside of Neo Geo coding, so please assume I am a beginner when answering. Hopefully this is something simple. Thank you!