The benchmark looks at This comparative is based on 20 groups of benchmarks including boot time, processor, 3D, USB, IDE hard disk, WarpOS emulation, 68k emulation, and more. It's written entirely in Foreign (French this time around), so I had to combine my years of learning French in high school (compulsory in The Netherlands) with the powers of Google Translate to find out the results.
The tables with numbers are pretty self-explanatory, and the conclusion couldn't be clearer: MorphOS 2.3 runs circles around AmigaOS 4.1 in almost every area. Especially when it comes to USB, MorphOS' Poseidon stack is considerably faster than AmigaOS' Sirion stack.
It is important to note, though, that AmigaOs 4.1 for the Pegasos II is still in its bets stage, so things can certainly improve once it moves out of beta. The test machine was a Pegasos II with a 1Ghz G4 processor, 1GB of RAM, an Ati Radeon 9250 video card with 128MB of RAM, and an ATA100 750GB hard drive.