Using Go's profiling tool with its "source" view: I used "go tool pprof -http=: cpu.prof", where cpu.prof was generated by "go-1brc -cpuprofile=cpu.prof -revision=9 measurements.txt".
This is the biggest take-away from this post to be honest; had no idea it could do anything like that. Sometimes it's the little things...
You can get something similar with the CLI using:
go tool pprof -weblist='mypkgname' cpu.out # Generate HTML and open
go tool pprof -list='mypkgname' cpu.out # Generate text to stdout