Optimize 'social' plugin on cold load

[oprypin]

Measuring the build times of 'insiders' docs without cache as follows:
rm -rf .cache/plugin/social && .venv/bin/mkdocs build 2>&1 | grep built
I get these results after each commit (2 measurements each to make it more reliable):

-----before
INFO     -  Documentation built in 8.46 seconds
INFO     -  Documentation built in 8.43 seconds
-----(Optimize social plugin: cache font objects)
INFO     -  Documentation built in 8.40 seconds
INFO     -  Documentation built in 8.42 seconds
-----(Optimize social plugin: reuse resized logo)
INFO     -  Documentation built in 7.78 seconds
INFO     -  Documentation built in 7.79 seconds
-----(Optimize social plugin: cache word width computation)
INFO     -  Documentation built in 7.11 seconds
INFO     -  Documentation built in 7.11 seconds
-----(Optimize social plugin: parallelize image saving)
INFO     -  Documentation built in 5.41 seconds
INFO     -  Documentation built in 5.52 seconds

Build times with cache are not affected.

[squidfunk]

Thanks for the PR, this look very promising.

Regarding concurrent.futures – is this Python 3.7+ compatible? That's our current minimum version:
https://github.com/squidfunk/mkdocs-material/blob/master/pyproject.toml#L37

[oprypin]

Sure it's compatible. Always easy to check.
https://docs.python.org/3/library/concurrent.futures.html

New in version 3.2.

[squidfunk]

Thanks! Commits were merged into #4628.