This saves ~10% in the benchmark.

Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>

Enumerating rather than using a while loop saves significant CPU when
looking for an unquoted character. This ends up improving the benchmark
~20% on its own.

Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>

Split the term into the label name and label value portions in one swoop
rather than starting from the beginning to find an = character after
already going through the full term. This saves ~5% on the benchmark.

Signed-off-by: Chris Marchbanks <csmarchbanks@gmail.com>