> Technically the patch LGTM. But we should find the cause of the regression in some benchmarks. The benchmark is on Sandy Bridge (Core i5 2400) and I didn't use PGO build. perf_event reported branch-miss rate increase at cpickle's save function. I'll rerun benchmark with PGO build. I hope PGO is friendly with CPU branch prediction, like L1/L2 cache. Anyway, recent amd64 CPUs have more large branch history. > And would be nice to extend the optimization to C functions. > In any case this optimization is worth mentioning in What's New. I'll do them.