Just where did you get your dhrystone 2.1 benchmarks?
There are two versions. One (from the Aminet, the WhetDhryStone benchmark - apparently compiled without optimisation), and a second one (compiled with -o2 switch). The "optimised" version was used in "our" tests vs Mirari because geennaam used the optimised one when testing Mirari on Linux.

Here it is for you to try. It's the same code from Aminet, just compiled with -o2.