It took me a day to understand the tooling required to get AFL working. Now I can spin up a new test case for a library within a couple hours. Once you have the test case, then it is CPU bound. I had on one series of tests, of the baresip sip library libre, running across 4 machines(24 cores each) for a day before it was 100% sure it had tested every code path looking for a SIP protocol decoding error through fuzzing.