Tl;Dr Cgo calls take about 40ns, about the same time encoding/json takes to parse a single digit integer. On my 20 core machine Cgo call performance scales with core count up to about 16 cores, after which some known contention issues slow things down. Disclaimer While alot of this article argues that “Cgo performance is good actually”, please don’t take that to mean “Cgo is good actually”. I’ve maintained production applications that use Cgo and non-trivial bindings to lua.

Cgo calls take about 40ns, about the same time encoding/json takes to parse a single digit integer. On my 20 core machine Cgo call performance scales with core count up to about 16 cores, after which some known contention issues slow things down.