apply_fix is too slow

[sk-]

Currently apply_fix is too slow. I reckon this is due to the fact that if a file has many violations, the linter will be run as many times. For LibCST it too several minutes to just fix one of the affected files.

The code says:

Applying a single fix at a time prevents the scenario where multiple autofixes combine in a way that results in invalid code.

What do you think of applying all the fixes with disjoint line ranges?