Investigate cython descriptors for orm attributes

[CaselIT]

It seems that they provide a fair bit of advantage compared to python descriptors.

See #4462 (comment)

[CarlosEduR]

@CaselIT I've been interested about performance, is there anything I could help here somehow?

[CaselIT]

Hi @CarlosEduR. The orm may not be the easiest part to interact with, but if you want to try, by all means.

Did you have something in mind regarding what part of performance were you interested in improving?

In this issue the idea would be to try and extract the base orm descriptor so that they can be compiled using cython.
This is assuming that the quick test done in the linked comment holds for the actual sqlalchemy use case

[CarlosEduR]

@CaselIT I don't have anything in mind yet, just got interested and curious about it. I'll take a better look at the base orm descriptor. I have never worked with cython, but that's interesting...

[CaselIT]

If you want to try it, the general idea here could be to extract the basic functionality in a superclass, that could be compiled to cython.

You can look into BaseRow in lib/sqlalchemy/engine/_row_cy.py for an example

Also note that it may be that it makes no difference in a real use case, I have just done the simplest test in the referenced comment