I've had similar frame rate issues with my cabinet that has a CRT in it, and in fact I have a second cabinet with a CRT and tried my emulation set up with it, and it also has the same issue. My story is different based on the game I was trying to get it to work with Cliff Hanger but I was able to get it working with a patch and great help from xx0To TOxx, which was great but as I said I had a different problem, which I rectified the balance after the patch by bringing the M2V into Premier, but it was a hassle. Unfortunately it's not a perfect solution, but for me it works at the moment, but hope to find a better solution in the future. I would try the patch to be honest it might almost solve your problem.