switch on first char benchmarks

```
Benchmark                           Mode  Samples   Score   Error
baseline                            avgt       10   6.706 ± 0.127
bigIfElse                           avgt       10  23.672 ± 0.188
bigStringSwitchWithFreshString      avgt       10  23.902 ± 0.299
bigSwitchFirstChar                  avgt       10  22.172 ± 0.648
smallIfElse                         avgt       10  14.188 ± 0.503
smallStringSwitchWithFreshString    avgt       10  19.266 ± 0.144
smallSwitchFirstChar                avgt       10  13.641 ± 0.186
```