More information would be helpful (system software, RAM, etc.). However:
The game is likely running in emulation on your PowerBook rather than natively. Running native 68k software on a 68040 would very probably be faster than running it on a (cacheless?) and early G3. A faster G3, or a G4 or G5 might do better, for instance, as might a 604e, which was said to be good at emulating 68k code.
Maybe try it with Speed Doubler installed, which dramatically improves emulation, and which was seemingly less dependent on processor caches than the code Apple provided, and make sure you allocate the game enough memory by changing the settings in the "Get info" panes?
The game is likely running in emulation on your PowerBook rather than natively. Running native 68k software on a 68040 would very probably be faster than running it on a (cacheless?) and early G3. A faster G3, or a G4 or G5 might do better, for instance, as might a 604e, which was said to be good at emulating 68k code.
Maybe try it with Speed Doubler installed, which dramatically improves emulation, and which was seemingly less dependent on processor caches than the code Apple provided, and make sure you allocate the game enough memory by changing the settings in the "Get info" panes?