Shin Megami Tensei: Persona 3 Portable - ULUS10512

[Phrourarch]

OK, this is really weird. About 3 months ago, I got P3P running very well. "50-60 FPS in Tartarus" well. Not flawless, but perfectly playable as far as I'm concerned. Yesterday, I went back to it, and the frame rate struggles to get past the 30FPS mark. I'm quite certain that I'm using the same settings as back then: vertex cache enabled, GE screen saved to textures. No hardware changes were made to my PC.

Initially I thought that the emulator development team had to make some performance sacrifices in the name of increased compatibility. I downloaded an older build (r2043), but that didn't help, so it's not the issue. Then I thought it was AMD that messed the drivers up and decided to roll those back. Didn't help. Finally, I figured that my Windows installation could have gotten bloated over the time, so I reinstalled Windows, but no result.

I'm completely lost at this point. What is it that I'm doing wrong? I know my PC is capable of running this game at a decent frame rate because it did just that mere months ago. If that helps, I have an Intel i5 750 2.67 GHz, a Radeon 4670 512 MB and 2GB of RAM. The video card and the amount of RAM aren't much by today's standards, but again, they used to suffice.

Oh yeah, enabling shaders catapults the frame rate all the way to 60FPS, but completely messes up everything that is 3D.