Mutative: immutable updates without the spread syntax

Mutative lets developers write mutations against a draft to produce a new immutable state, avoiding manual spread copies at every level. It also supports arrays, Set and Map, along with patches and optional freezing.

Its benchmarks report a geometric mean 3.6 times faster than Immer with matched settings, or 6.6 times with each library’s defaults. Results vary by workload; hand-written reducers remain faster in most of the cases shown.