Usually garbage collection does improve alot of benchmarks, just look at the hans boem gc benchmarks.

Back in the day, the cheat was to set up the GC so that the GC happened outside the timed portion of the benchmark. You know what's faster than the fastest GC? Not doing it.

The two extreme outliers I see are labeled "aead/clx192q/opt,-O3" and "aead/schwaemm128128v2/opt,-Os" according to clicking on the points with devtools. aead/schwaemm128128v2/opt,-Os looks like it is almost at 0x. 1x is at about y = 659 and that test is at 769 out of I guess 780 based on the graph.