From my own perspective of cheating in the past and dealing with speed hackers as a staff member, the majority of players will use a standard accelerator to speed up their framerate, therefore speeding up their movement in-game.
No **** right? As Asaiki stated, the Ol'West, Era and Zone servers all have a frame rate checker that determines every player on the server's framerate, every second or so. A lot of nubs will get Insta-jailed as soon as they turn the thing on and run around like sonic. Last time I checked, Classic doesn't have one of these.
However the slightly more intelligent nubs will try and setup hotkeys on cheat engine that toggle the accelerator on/off so that they speed up by maybe 1.2x their framerate for half a second, and then back to the standard 1x framerate everyone has. This is to avoid the server check and still gain a considerable speed boost in the process, Ive seen it countless times.
But if they were really smart and knew the game mechanics, they would just find the default walkspeed value of the server and just adjust that, as no server has a detection for that. Not advisable though, since this type of speed hacking is blatantly obvious - hence why a lot of speed hackers in races just toggle an accelerator on/off