I'll go ahead and put forward my specs just to get the formalities out of the way since I know people will ask:

AMD Athlon 64 X2 Dual Core @3.0 GHz
4GB RAM
Nvidia GeForce GTS 250 video card
Windows 7 Premium 64-bit

I'm using version 0.9.7 of PCSX2. I won't go into details about what plugins/settings I'm using because frankly that's not my problem. I've tweaked the settings and plugins to the best I have been able to and I can get the games to run fine. My problem comes when I get to the actual gameplay and find I have major slowdown. Tweaking the settings helped with this somewhat (especially in cutscenes and the like) and I can run the game fast enough to be able to play it, but the slowdown is still extremely annoying. I'm pretty sure it's also the cause of the sound being pretty garbled.

I'm pretty certain that my processor is the bottleneck. I don't have the best processor in the world, but I don't think it's even a year old. I also don't have it overclocked. I have a gadget on my desktop that monitors how much of my CPU I'm using at a glance, and when running PCSX2 (been trying to play MGS2 and RE4, have the same issues of slowdown in both games) my CPU usage maintains around 70-95% pretty much constantly. Menus run fine, and I've gotten cutscenes to run perfectly fine, but the actual gameplay is where I'm experiencing the slowdown.

I could try overclocking my CPU a bit to see if it runs any smoother, but I don't really want to do that. I don't want to overclock just to be able to emulate PS2 games, especially when my CPU is already close to full throttle already when trying to play. I just don't know if it's worth it.

What ticks me off is the games seem to work great with no major graphical or audio issues, yet my computer just seems barely under the threshold to be able to play the games smoothly. I realize emulating takes a bit more than running a game normally, but I find it lame that I can run pretty much any game from the last year at the highest graphical settings without my computer missing a beat, but I can' emulate games that are over half a decade old.

I can emulate Dreamcast pretty much perfectly as well. I played Code Veronica for a couple hours the other day without experiencing slowdown in the slightest, and even though the Dreamcast is a bit older than the PS2 I still consider them in the same generation of consoles.

Should I try overclocking my CPU?