Your question is very very fuzzy, it very much depends on what kind of
application/task you want to have,
For example if you use RDBMS, mostly any backend efficiency will be
stripped down by database operations, that’s definitely the place where
(if you have working solution already) you may not win anything by just
switching from to nginx.
I would address python side of your question by recommending these two
(not mine) performance reports:
You should do something like that before you’ll choose any of the
solutions from those that may for you.
What load would you expect in next year or two, what CPU load your
application generates on that load, what server resources you have to
work with and so on.
Rule of the thumb is not to plan scaling more than 10 times from what
your projected load is (taking into account natural growth that you have