It appears there's actually a project benchmarking a bunch of Z80 C compilers: https://github.com/z88dk/z88dk/wiki/Benchmarks https://github.com/z88dk/z88dk/wi

It appears there's actually a project benchmarking a bunch of Z80 C compilers: https://github.com/z88dk/z88dk/wiki/Benchmarks https://github.com/z88dk/z88dk/wiki/Benchmarks Among IAR, there's also HITECH C Compiler, which, when it is not disqualified for bad results, seems to have some impressive numbers at times. (And the project's own C compiler, when it does not hit a pathological case.)