Compare go test -bench=... results and print nice statistics.
https://pkg.go.dev/golang.org/x/perf@v0.0.0-20211012211434-03971e389cd3/cmd/benchstat
$ benchstat old.txt new.txt
name old time/op new time/op delta
GobEncode 13.6ms ± 1% 11.8ms ± 1% -13.31% (p=0.016 n=4+5)
JSONEncode 32.1ms ± 1% 31.8ms ± 1% ~ (p=0.286 n=4+5)