Code generated for

	copy(posb[2:], posBuf[i*6:])
	pos := int64(binary.BigEndian.Uint64(posb[:]))

was awful.

name         old time/op    new time/op    delta
IndexLoad-4    3.06ms ± 0%    2.49ms ± 1%  -18.71%  (p=0.000 n=9+10)