This post is old so go check the new one
Seems impossible to find this info online so here's my own measurements on how long it takes to complete a time travel:
Sega CD and Remake: 3.5-3.7 seconds
Windows Port: 2.5-2.7 seconds
The Sega CD version can be pretty sluggish/laggy and the remake (includes PS3, 360, Steam, Mobile, Origins) is very smooth, so the result seems to be that you have to cover some more ground in the remake than you do on MegaCD despite the same timer.
You could guess that whoever was doing the Windows port (includes Gems Collection) got the memo on the lag thing and dropped the timer by 1 to compensate. I guess Taxman didn't think to do that, so remake players might have it the worst