I recently got a PC rig capable of entry-level VR, so I assumed I'd be able to play PS2 emulated games easily enough. Boy was I wrong, Shadow of the Colossus (the only game worth playing in my book ;-) ran up to 70-80% performance, and dipped down to 10-50% performance when I looked at high-poly regions, depending on the graphics settings I chose. (On Windows, with PCSX2 1.4, you can see the framerate % in the window titlebar.)
Then I found this Reddit link: https://www.reddit.com/r/PCSX2/comments/3bjpos/is_pcsx2_running_slow_on_your_knowingly_highend/
The gist of that advice is: A modern gaming PC is likely having trouble with PS2 emulation because it's overperforming on some calculations (magic?), not underperforming. In many cases one key setting will get your PC's behavior more "in sync" with what the game needs, and then everything is super smooth. So that would mean you can 1) pick a graphics level default, then 2) uncheck "preset" and play around with settings one by one until you find a marked improvement.
I was a bit skeptical (I thought I'd tried all the relevant settings anyway) but I gave this a shot, and it worked... and more than worked. In my case, for whatever reason, one setting made all the difference:
- Set presets to 3, then uncheck the "preset" checkbox (allows you to fine-tune)
- Under VU settings (something to do with the virtual machine?), change the VU0 setting from "microVU Recompiler" (default) to "Interpreter".
After making this one change, I can now ramp up the graphics and texture settings to near their max, then switch to 4x the native resolution, all with 98%-105% framerate. This also resolved the stuttering / "metallic" quality to the audio, though again I have no clue why.
Next step: make it work in VR with VorpX...