Performance Profiling

[OAGr]

We currently don't have any real performance testing/profiling. This is pretty important for optimizing performance.

[OAGr]

From @berekuk :

The way snapshotting workflow could work:
first you write tests (in case of UI, just code that renders html, in case of Squiggle, squiggle code)
you run the tests for the first time, they respond "there's no snapshot associated with test X, creating..."
then you commit the tests and the snapshot files generated by tests
after that when you run tests, they pass if snapshot matches the output
if snapshot doesn't match and you run in interactive environment then you get asked "do you want to update the snapshot? here's the diff"
you take a look and decide if the update is expected or not
the diff is nice and colored and if the reducer log would increase significantly that would be obvious by comparing the amount of green stuff and red stuff
if the update is expected, answer "confirm" and snapshot files get overwritten on disk; then you commit them together with your changes
if update is unexpected then you fix your code