I mostly picked it up by working on interpreters and compilers, doing performance analysis on the generated code, trying to find all papers on the subject (some

I mostly picked it up by working on interpreters and compilers, doing performance analysis on the generated code, trying to find all papers on the subject (some of them good, some of them really bad - you have to filter them yourself), and reading about what other implementations have been doing. It's also important to be able to run experiments quickly; you don't want to have to get every patch production-worthy before doing basic performance analysis.