Various non productive overhead

[pacak]

I noticed that argmin collects statistics about how many times functions are called, for example here and in a few other places

argmin/crates/argmin/src/core/state/iterstate.rs

Lines 1358 to 1363 in 35e00e2

	fn func_counts<O>(&mut self, problem: &Problem<O>) {
	for (k, &v) in problem.counts.iter() {
	let count = self.counts.entry(k.to_string()).or_insert(0);
	*count = v
	}
	}

Both allocations and hashing can be expensive compared to solving, in fact I hacked examples/newton to skip console logging and to run the computation a bunch more times taking care of blackboxing the results - counting is responsible for about 20% of all the time.

And if I disable timing (Executor::timer) along with removing counting - newton example is suddenly 30% faster...

Any objections if I try to shove it out of the way? Timing doesn't seem to be used unless there are observers - should probably be disabled unless needed, counting can probably be made optional or made into observer, not 100% sure yet.

[stefan-k]

That's not great. Thanks for investigating! I agree, both should be disabled if no observers are used. And even if observers are used, it should be possible to turn off function counting. A PR would be highly welcome! The only thing I would object to is turning function counting into an observer, because I plan to add stopping criteria based on the number of function evaluations in the future.