Rough comparison of input lag in three ports of Vampire Savior on my set-up, which includes a Hori HRAP V 2017 arcade stick, a 4x2 component matrix switcher, an OSSC, Brook Super Converter adapters, and a 5ms display lag monitor. On a computer, if you're playing this video at 60 fps, you can pause playback, then advance one frame at a time by pressing the "." key, and count along with me the frames that go by between the arcade stick's light punch button being fully pressed down, and Morrigan beginning to play her light punch animation--just make sure the video playback quality is at a 60 fps setting in your YouTube player. I counted the following delay frames for the games:
Darkstalkers 3 (PS1): 3 frames of delay
Vampire: Darkstalkers Collection (PS2): 5 frames of delay
Darkstalkers Resurrection (PS3): 4 frames of delay
I was surprised that the PS1 port beat Iron Galaxy's PS3 port--their famous earlier PS3 port being the ~2 frame delay (2.5 on my setup/test) 3rd Strike. I shouldn't have been that surprised though, I suppose--the lowest lag version of SFII I have is on PS1, after all!
This is a totally unscientific test and only really relevant to the performance of other games tested on my current set-up! I plan on testing the version of Vampire Savior coming later this month to my PS4 in Capcom Fighting Collection. Will it beat the PS1 port??
I recorded the video on my Google Pixel 3a phone, with its Camera app set to 60 fps recording.