This code is a example to validate performance using append or not in golang
go test -benchmem -bench .
goos: darwin
goarch: arm64
pkg: poc
BenchmarkTestWithLength-8 115262 9422 ns/op 81920 B/op 1 allocs/op
BenchmarkTestWithoutLength-8 30625 39379 ns/op 386298 B/op 20 allocs/op
BenchmarkTestNotUseAppend-8 285175 4103 ns/op 81920 B/op 1 allocs/op
PASS
ok poc 4.218s