I figured that would be the case with games like X-com running too fast. The collection version of X-com had a program called MoSlo.exe and you had to adjust the percentage in the command line. Still, the game would run choppy and just didn't feel right.
Funny how I went from a 386sx 16mhz to a Pentium II 400mhz from 1991 then 1998. I missed out big time with 486DX and Pentium 1, which was the golden age of 2D PC gaming. I especially remember some greats from '96 and up: Doom 1 and 2, Heretic, X-Wing + Tie Fighter, Dark Forces, Lucas Arts Games (Sam and Max, Full Throttle, The Dig, etc...), some newer Sierra Adventure games, Dark Seed, and most importantly Wing Commander 3.
Thank god I had a PlayStation 1 and was able to play Wing Commander 3+4, Dark Forces, Rebel Assault 2, X-Com UFO Defense, command and conquer games and a decent version of Doom 1+2 combined. Still, I missed out on a lot of good PC games overall.
DOSBox just doesn't work all too well for quite a few games. They can't seem to get the Cycle CPU timing right and there really isn't a smooth Direct X support for the VESA DOS type graphics (Is that right... VESA is the DOS video processing method?). FPS games run shotty as hell and the FMV in Wing Commander 3 skips if you don't constantly adjust the Cycle speed between it and the gameplay.