go memory-optimization data-structures lookup-tables benchmark

ConstMap replaces Go maps with 6x memory savings

Binary fuse filters compress string-to-uint64 lookups from 56 bytes/key to 9 bytes/key with 3x faster latency on immutable datasets.

June 10, 2026

Summary

For large read-only lookup tables (logging IDs, config mappings, feature flags), this trades one-time construction cost for sustained memory efficiency and cache locality gains—critical when map size exceeds L3 cache. Reduces operational memory footprint without code rewrites.

Why it matters

Implementation verdict

Drops in as constmap.New() with identical API to Go maps. Worth adopting now for immutable string→uint64 mappings over 100k entries; not suitable for frequently modified maps or other value types. Serialize to disk to avoid reconstruction overhead.

Sources

1.The map may use over 50 bytes per entry
2.you can reduce the memory usage down to almost the size of the keys, so about 8 bytes per entry
3.ConstMap is nearly 3 times faster than Go's standard map for lookups
4.56 bytes/key
5.9 bytes/key
6.7.4 ns/op
7.20 ns/op

Dev Signal

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