I don't understand what you are saying.
I'm saying it is slower on docker due to container startup, pulling images, overheads, working out what incantations to run, filesystem access, network weirdness, things talking to other things, configuration required, pull limits, API tokens, all sorts.
Versus "go run"
But usually it's not "considerably". Obviously setting up the container environment takes time but it should be well under a second per build.
Wow! You are right! Running go build on host instead of container is 1.16 times faster! A whopping 435ms difference! Amazing!
/tmp/gitea $ hyperfine -p 'go clean -cache' 'make backend' 'docker run --rm -v $PWD:/build -v $HOME/.go:/go -w /build golang:1.22.3 make backend'
Benchmark #1: make backend
Time (mean ± σ): 2.766 s ± 0.021 s [User: 8.429 s, System: 1.590 s]
Range (min … max): 2.732 s … 2.800 s 10 runs
Benchmark #2: docker run --rm -v $PWD:/build -v $HOME/.go:/go -w /build golang:1.22.3 make backend
Time (mean ± σ): 3.201 s ± 0.034 s [User: 9.9 ms, System: 7.7 ms]
Range (min … max): 3.135 s … 3.235 s 10 runs
Summary
'make backend' ran
1.16 ± 0.01 times faster than 'docker run --rm -v $PWD:/build -v $HOME/.go:/go -w /build golang:1.22.3 make backend'
> which is considerably faster than on docker
And we are curious why it is like so because we not only understand how to do stuff without containers, we also understand how containers work and your claim sounds off.