Storing concrete values into interfaces often cause allocations, which has a larger impact on performance than inlining.

Yeah I was really surprised by how much of a performance difference it made when calling variadic functions that support `args ...interface{}`. Literally every since call is going to be an allocation of multiple parameters when passing structs without a pointer

You have to manually collect and then apply the profile though (very few teams do this). A proper solution is doing a whole program view optimization (at least like the one done by .NET's NativeAOT). But typically of Go design philosophy, a stop-gap solution was chosen instead.

> Go compiler seems to have trouble with inlining

not "have trouble", a deliberate design to keep compile times fast and (emitted) code size reasonable

Ah yes, whichever it is, always design.