EFB2RAM is required for a number of effects and the targeting computer, but the game will work without that (and faster).
Skip EFB Access From CPU seems to make it faster, but others might have done more testing.
The faster the texture cache setting, the slower the targeting computer will update. Medium seems to work mostly okay, Safe of course works perfectly.
HLE audio works fully in RS3, but in RS2 it seems to cause crashes in some specific places, like the start of FMVs (like at the end of the trench run). Nobody knows why yet.
Fast Depth off is required for zfreeze to work.
Virtual XFB is required; some scene transition effects and such will be glitched without Real XFB, but the game otherwise works fine without it.
Underclocking doesn't seem to cause any issues; it's a great way to get a whole bunch of VFPS if your computer isn't fast enough, in my experience.
Skip EFB Access From CPU seems to make it faster, but others might have done more testing.
The faster the texture cache setting, the slower the targeting computer will update. Medium seems to work mostly okay, Safe of course works perfectly.
HLE audio works fully in RS3, but in RS2 it seems to cause crashes in some specific places, like the start of FMVs (like at the end of the trench run). Nobody knows why yet.
Fast Depth off is required for zfreeze to work.
Virtual XFB is required; some scene transition effects and such will be glitched without Real XFB, but the game otherwise works fine without it.
Underclocking doesn't seem to cause any issues; it's a great way to get a whole bunch of VFPS if your computer isn't fast enough, in my experience.