Try the
Windows 8 Performance "Patch" (works in Win 7 and 10, as well), and see if that makes a difference when Alt-Tabbing.
In the configuration program, try switching to Software mode, rather than Direct3D.
Windows 8 slow graphics problem fixed using WineD3DYou can also try using the disk version of the configuration program to set the game to run in Direct Draw mode. Rename or move the existing configtool.exe and NlsEng.dll files in the install folder, and extract the disk versions from this
zip file.
You might be able to get the game to run in a window, though it is a little finicky, and people have reported mixed results.
Is it possible to switch this game to window mode?Windows Borderless Gaming app