@Matt_H
In a similar vein, performance of MOL is greatly reduced because it can't access hardware resources directly and has to use an emulation layer. I'd imagine there's also a performance hit with AROS Hosted vs. AROS native (the AROS guys can correct me on this), and with Windows running through Parallels vs. Windows running natively. Even old DOS apps running through Windows 95 are slower.
From joe user pov I think on can hardly figure the hit (gui wise), probably on benchmarks or on intensive apps... but it been a while since I ran AROS in linux, can be wrong on my judgment.