next.js

dddf2c76 - Improve SSR throughput with micro-optimizations and webstreams improvements

Improve SSR throughput with micro-optimizations and webstreams improvements Merges 6 separate TransformStream instances into a single unified createUnifiedSSRTransformStream for the dynamic SSR path, eliminating intermediate stream allocations and microtask hops per chunk. Adds opt-in perf marks (NEXT_PERF_MARKS=1) with zero overhead when disabled, benchmark runner with CPU profiling and phase timing, and unit tests covering behavioral equivalence between legacy and unified transform chains.