probably easier just to link to this thread:
http://board.byuu.org/viewtopic.php?f=3&t=2024&sid=84955d6f617d87518566b481eedc6de3
byuu’s the author of bsnes, probably the most accurate emulator for any console. his discussions on PC input lag, why it’s a thing, and people running tests to back it up are pretty useful here. basically the tl;dr version of it all is that playing any emulator on any modern computer is going to incur significant audio and visual lag and there’s no way to avoid it on modern OSs. in theory you could take direct control of the video and sound hardware and reduce lag that way but that’s not really possible outside of like DOS. quick excerpt from the thread which summarizes it:
It’s a problem inherent to all emulators. Nothing I can do about it.
We need absolute control over the screen and sound card to output samples dynamically as they are generated.
Until then, we have to buffer entire frames of video and blocks of sound, which causes measurable lag of up to ~30ms. Then the OS does its own buffering for composition of multiple windows and audio streams, and you add another ~30ms on. Then add another ~10-30ms for your monitor and sound card to refresh, and you can detect it. The lag is in video and sound, it’s because of this that it feels like input lag. But the input is polled with ~5ms accuracy.*
I can’t play Ninja Gaiden worth a damn under emulation, but I am pro at it on real hardware.
( let’s be real, the hardware will never be made, as it’d only really benefit emulation.)*
same would go for FBA as well. add on that it’s really hard to get FBA to crackle audio without a big audio buffer and it’s even worse. I think that’s the strong argument for OE > FBA (for offline play). We know OE has 4f input lag which probably matches real hardware. for FBA that is probably not the case.
there’s a feeling from a lot of people that FBA runs too fast compared to CPS3. but when we ran tests last year trying to figure that out we didn’t discover much. my theory is the extra couple frames of lag makes things harder to react to, feel faster, etc. there might be more to it but no one has shown anything.