Remove the use of io.ReadAll in http.parsePostForm to avoid converting
the whole input from []byte to string and not performing well
space-allocated-wise.
Instead a new function called parsePostFormURLEncoded is used and is
fed directly an io.Reader that is parsed using a bufio.Reader.
Benchmark:
name old time/op new time/op delta
PostQuery-4 2.90µs ± 6% 2.82µs ± 4% ~ (p=0.094 n=9+9)
name old alloc/op new alloc/op delta
PostQuery-4 1.05kB ± 0% 0.90kB ± 0% -14.49% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
PostQuery-4 6.00 ± 0% 7.00 ± 0% +16.67% (p=0.000 n=10+10)