We all know: Stalin brutally optimizes. Iirc it is still one of the faster scheme compilers. Sure, Chez will probably run more stable, but I for numeric code or when the full program optimization can work it's magic in ways that other scheme compilers can't it produces faster code than all other compilers.

Last time i checked it was the most capable at optimizing type inference in the presence of mutation. Where most other schemes just did boxing, Stalin produced nice and fast code.