This reduces the complexity of the comparison and gets rid of the heap
allocation on every match.

Benchmark before/after (`go test -bench . -benchtime 3s -count 5 -benchmem`):
```
name                old time/op    new time/op    delta
Matches/success-32    66.9ns ± 1%    15.7ns ± 0%   -76.47%  (p=0.016 n=5+4)
Matches/fail-32       27.9ns ± 0%    12.4ns ± 2%   -55.70%  (p=0.016 n=4+5)

name                old alloc/op   new alloc/op   delta
Matches/success-32     5.00B ± 0%     0.00B       -100.00%  (p=0.008 n=5+5)
Matches/fail-32        0.00B          0.00B           ~     (all equal)

name                old allocs/op  new allocs/op  delta
Matches/success-32      1.00 ± 0%      0.00       -100.00%  (p=0.008 n=5+5)
Matches/fail-32         0.00           0.00           ~     (all equal)
```