This is simply a compiler which compiles one basic block at a time, basic blocks being defined as single-entry, single-exit sequences of instructions. It also only compiles "hot" blocks that have been executed a few hundred times, the idea being to avoid wasting time compiling code that only runs once or very few times (e.g. initialization code). I could have tried hard to make the Higgs interpreter faster, at the cost of tasteless kludges and largely increased code complexity, but I don't think it would have been worth it, especially now that I've shown that 4 days of work can yield a simple JIT compiler producing 500% speedups.