Understanding the performance costs of generating functions on the fly

[bkamins]

@pdeffebach

in the meantime we should add benchmarks for functions inside transform compared to their counterparts outside of transform .

It would be great if you run independent benchmarks on the PR I linked. I have run such benchmarks and that is why I have added @nospecialize there (but benchmarking is tricky so it would be great to have some independent tests).