RetroArch is capable of next-frame responsive time. This means that there should be no nearly no perceivable difference in terms of input latency from real hardware, FPGA/clone or original hardware.
On top of all that, there are various settings you can configure to optimize the results even more.
RetroArch is truly in a league of its own when it comes to input responsiveness, and it keeps confounding even us here at Libretro. Several independent researchers did their own research on RetroArch's latency and came away being quite blown away by the results, completely shattering several long-held myths that up until now had been accepted as gospel in emulation circles:
RetroArch shatters these myths. It has been demonstratedy by independent researchers that a next-frame response time (≤16ms!) achievable with RetroArch! This means zero frames of input lag is achievable, indistinguishable from real hardware.
Whoever told you that input lag was a given with emulators and that you needed FPGA in order to avoid this latency, should get him/herself acquainted with RetroArch. Post-RetroArch, latency indistinguishable from real hardware is perfectly possible!
Check out people's findings here on our forum and participate, don't just take our word for it! Link here.
"With Pitfall, I witnessed a response on the very next frame. In the video shown to the left, you can clearly see me hit the button near the end of one frame, and on the next, Harry jumps! Essentially no way to improve compared to original hardware. Pack it up. We’re done here"
"Ever since I tried Retroarch for the first time there was no doubt in my mind that it was the future. It overcame the crippling input lag that plagues many stand alone emulators."
"[With RetroArch], it is possible to get to the same input lag as the original hardware, which may be as little as whatever is left of the current frame. At 60fps (16ms) this could be anywhere from 0ms to 16ms, which averages out to about 8ms. There is no room for improvement above that as far as the software is concerned."
RetroArch provides you with all the tools you need to combat latency in your games. This includes options such as: