JIT? Improve CPU cache usage Step 1: Decrease overall data Step 2: Better data locality and less indirections Step 3: Save the world! zval size reduced from 24 to 16 bytes Hashtable size reduced from 72 to 56 bytes Hashtable bucket size reduced from 72 to 32 bytes Immutable array optimization New memory allocator similar to jemalloc Faster hashtable iteration API Array duplication optimization PCRE JIT enabled by default Precomputed string hashes Fast ZPP (ZendParseParameters) implementation Faster stack-allocated zvals (instead of heap) Optimized VM calling Global register variables with gcc 4.8+ plus hundreds of micro-optimizations JIT?