Go 1.24 replaces the old bucket-and-overflow map internals with a Swiss Table-inspired design to improve cache locality, lookup speed, and memory efficiency.

Deep dive on Go’s map internals in Go 1.24 and how the runtime moved from the classic bucket + overflow-chain design to a Swiss Table-inspired implementation:

  • what changed structurally in the runtime
  • how control bytes and h2 filtering reduce wasted key comparisons
  • why this improves cache behavior and practical load factors
  • Go-specific constraints (iteration semantics, GC integration, incremental growth behavior)
  • benchmark context and caveats (microbench wins vs smaller app-level geomean gains)
  • current trade-offs and open performance areas