There are already a couple of cross-language comparisons between Crystal and other languages based on (arbitrary) micro benchmarks. The Are-we-fast-yet benchmark suite (see https://github.com/smarr/are-we-fast-yet) includes representative benchmark implementations of different languages, whereby the authors consciously paid attention to an idiomatic use of the respective language. See here for more information about the implementation: https://stefan-marr.de/papers/dls-marr-et-al-cross-language-compiler-benchmarking-are-we-fast-yet/.I run the benchmarks for some of the supported languages on my i386 Linux machine. Here are the results: http://software.rochus-keller.ch/are-we-fast-yet_crystal_ruby_lua_node_i386_results_2020-12-10.pdf.
The results are normalized to Crystal. The geometric mean of the normalized values shows that Crystal is about twice as fast as Node.js, about four times as fast as LuaJIT and about 25 times as fast as Ruby MRI.