Benchmark the initialization cost of your packages or programs.
cd $(mktemp -d); go mod init tmp; go get mvdan.cc/benchinit
This includes the cost of init functions, plus initialising globals. In other
words, a package's contribution to the slowness before main is run.
Requires Go 1.12 or later.
Benchmarking a single package is simple:
benchinit cmd/go
You can also include all dependencies in the benchmark:
benchinit -r cmd/go
Finally, like any other benchmark, you can pass in go test flags:
benchinit -r -count=5 -benchtime=2s cmd/go
This tool was result of a discussion with @josharian. You can read more about Josh's idea in his blog post.