Add some benches and some internal cleanup

[michaelkirk]

• [x] I agree to follow the project's code of conduct.
• [-] I added an entry to CHANGES.md if knowledge of this change could be valuable to users.

• [🌮] I ran cargo fmt

No changes in behavior, just wanted to do some cleanup and add some additional baseline benchmarks.

[lnicola]

bors r=urschrei,lnicola

[bors[bot]]

Build succeeded:

• wkt