Looks to me as if the game is running in software mode. Run the setup and choose hardware acceleration. I'm not familiar doing this through Steam, I do it via the game EXE file itself. To do this, create a shortcut of the Tomb2.exe file, then open the properties of this shortcut. At the end of the target/address field, add a space, then type -setup and click OK.
Now run the shortcut and the setup menu should appear. You can also try pressing Shift+F12 in-game to switch modes.
To further improve your PC TR2 experience, I recommend Arsunt's
TR2Main.
Guide here.