Add documentation about profiling and performance analysis

[DanielNoord]

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Type of Changes

	Type
✓	📜 Docs

Description

Closes #4067

While by no means perfect, this might be a good step towards better documentation on performance analysis. At least it shows users how to generate a useful profiler report.

[DanielNoord]

@DudeNr33 I wrote a little something just so we have this information somewhere and can refer to it. Please let me know what you think of it!

[coveralls]

Pull Request Test Coverage Report for Build 1623987012

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.708%

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Totals
Change from base Build 1617209026:	0.0%
Covered Lines:	14312
Relevant Lines:	15273

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💛 - Coveralls

[DudeNr33]

This is a great idea to document this for future reference!
Maybe a short summary what to look for in the results could be helpful.

I think besides the "general" profiling, a contributor might be interested in optimising a new checker they wrote. They are probably interested which method is called how many times, and what the most taxing portions of their code (both in total and cumulative time) are.

[DudeNr33]

Looks good! Thank you for documenting this!

[Pierre-Sassoulas]

I think only talking about the specific of pylint is good. We could add possible tools in the last part or remove the part where we explains how cprofile works altogether and link to the documentation instead. Performance inclined contributor are unlikely to need basic advises like this imo.

[Pierre-Sassoulas]

Great work, the basis for pylint getting faster 👌