Performance improvements

[kokroo]

I am making some ongoing performance improvements to the code. Although this won't matter much for a single run, it will create a measurable impact on execution speed and memory usage for bulk comparisons, for example, while comparing thousands of files.

I am making sure that the input and output stays the same for each optimized function.

Once I optimize the entire codebase, we can merge it.

@danielfromearth

[kokroo]

@danielfromearth I have fixed the issues raised by Pylint. I believe you will need to run the workflow manually, again, because my PR has not been accepted yet.

[kokroo]

@danielfromearth I saw you opened #12 . I am guessing this PR broke the output layout?

[kokroo]

Closing this in favor of a new pull request #263