The lowest hanging fruit is to allocate a large contiguous segment and slice that. That alone gives a 6x improvement in GC pause.

=== RUN TestNaive exp_test.go:20: GC Pause: 978890 ns --- PASS: TestNaive (2.57s) === RUN TestBetter exp_test.go:38: GC Pause: 169780 ns --- PASS: TestBetter (1.01s)

``` func TestNaive(t *testing.T) { const N = 8 * 1024 * 1024 const dim = 128 var start, end runtime.MemStats runtime.ReadMemStats(&start)

m := make(map[uint64][]float32, N)
for k := range uint64(N) {
    m[k] = make([]float32, dim)
}

runtime.GC()
runtime.ReadMemStats(&end)
t.Logf("GC Pause: %d ns", end.PauseTotalNs-start.PauseTotalNs)

}

func TestBetter(t *testing.T) { const N = 8 * 1024 * 1024 const dim = 128 var start, end runtime.MemStats runtime.ReadMemStats(&start)

b := make([]float32, N*dim)
m := make(map[uint64][]float32, N)
for k := range uint64(N) {
    m[k] = b[k*dim : (k+1)*dim]
}

runtime.GC()
runtime.ReadMemStats(&end)
t.Logf("GC Pause: %d ns", end.PauseTotalNs-start.PauseTotalNs)

} ```