for themes with many files and partials, the checks can take a very long time to run
digging into it, it seems that this is due to the normalizePath function being executed tens of thousands of times over the same strings
I tried optimizing the function but it wasn't easy, so the next best step is to precalculate the normalized paths when loading the theme, and then they're ready to go next time
this optimizes the check time of a particularly heavy theme from 5s to 1.7s on my local machine, and I bet slower machines get a bigger improvement
fixes https://github.com/TryGhost/DevOps/issues/3
normalizePathfunction being executed tens of thousands of times over the same strings