@Karlos
So your saying that your 1998 aftermarket addon CPU-card managed to outperform the 1987 (?) stock A3000 (A as Archimedes here) ?
Oh, my
1995 Apollo 1240 turbo totally wiped the floor with the Archimedes A3000

By late 1998 I was getting my BlizzardPPC, if I recall correctly.
However, it also outperformed the
Acorn RiscPC, which is the machine I was actually talking about. The example below shows the case stacking, my friends system was just the lower slice.

I suspect it might be that the ARM processor in said model had no floating point support though I doubt the 040 jpeg codec I was using at the time used FPU either.
One of the coolest add-ons in my friend's RiscPC was a 486 board for PC compatibility. It integrated rather well with the host system, which provided the emulated display within a window on the RISCOS desktop as well as the disk IO and everything else. Seeing it run Windows 95 was quite amusing

I think the machine was a 33MHz ARM 610. I could be wrong.