Refactor: performance and memory optimisations

[nothingbutlucas]

Hi!, how are you?

Well, I was looking at the project roadmap and one of the points is: Performance and memory optimisations of the Python implementation

This PR intends to work on this point. I started with the utilities. I'm uploading this PR now so I don't suddenly fall with 100 commits and a lot of changes. I hope the commits are explanatory and clear. If there is something that can be fixed or done differently, please let me know.

I think best way to move forward (If you want that), would be to keep working on this PR/Branch and keep adding commits... What do you think?

I keep working on the utilities or is there any particular module that consumes a lot of memory or performs badly?

~~By the way, I ran the tests and the 34 ran well with these new changes.~~

Also, I did not see any style guide defined, I saw that some files are formatted as black would do and others in another way, I think it would be good to define this, at least to start and that there is a coherence between the files of the repo.

Thank you!

EDIT: Ok, as far as I see, the tests do not cover the utilities, maybe it would be good to add tests for the utilities as well, right?