One of our ACLs at work relies heavily on Go regexp. The performance of evaluation is actually not too bad. What is quite terrible is the performance of *compiling* regexps.
I find this a bit surprising -- do you have numbers? Though even if compiling them is relatively slow it doesn't matter too much, because usually you're compiling once and evaluating many many times (e.g., in the case of a typical AWK script, you compile once and evaluate for each line in the input).
