avoid string expr in to_next_multiple

[Nomos11]

This is up to a factor 5-6 faster than before in the branch with min_quanta

[github-actions]

Test Results

    6 files      6 suites   7m 28s ⏱️
1 234 tests 1 172 ✅  62 💤 0 ❌
7 404 runs  7 032 ✅ 372 💤 0 ❌

Results for commit fec6ed3.

♻️ This comment has been updated with latest results.

[shumpohl]

In the future, I think it would be better to avoid free-style branch names on the github repo. For non-issue branches there are already a wide variety of folder prefixes. performance exists already

[shumpohl]

I'll make my own version

[shumpohl]

At some point it probably makes more sense to change the expression backend

[Nomos11]

At some point it probably makes more sense to change the expression backend

the next limiting factor would probably be .subs for pulses with heavy MappingPT usage. Sympy itself recognizes this is slow as an open issue sympy/sympy#22240

[shumpohl]

Ideally, we stir in a direction where the evaluations are not done at all, i.e. loop bodies are handled symbolically.

[Nomos11]

that's probably a more long term goal right? At some point, most hardware will probably need evaluations