perf: a bunch of optimization

[SimplisticMind]

This is a large one so if you want to just cherrypick - feel free to do so; with that out of the way, a few less obvious ones:
envfs.h - upwards of ~20%+ faster refreshing
moapplication.cpp - Qt elements render up to twice as fast
settings.cpp - most impactful settings got hoisted out, other ones aren't hot enough to really necessitate such hoisting too
fileregister.cpp - sortOrigins() - 4x faster compared to locking each file seperately

[Holt59]

Thanks for the PR, it would be easier and more likely to be accepted if you split it in smaller chunk because as it stands, it's complicated to review (and cherry-picking would take a lot of time).