~40% improvement over status quo (perf measurements are best-of-5)

### before

```console
$ time flake8 /dev/null

real    0m0.337s
user    0m0.212s
sys     0m0.028s
```

### after

```console
$ time flake8 /dev/null

real    0m0.197s
user    0m0.182s
sys     0m0.012s
```

I guess that if you don't have something python2 compliant to say. might as well say nothing at all
Also fix linter errors