Not talking about Rust here, so not really an answer, but in the film VFX industry (rendering in my case) pretty much all the high performance code is C++ or CUDA, and before we moved to c++11, I'd worked out that for STL iterators, at least in the 4.2/4.4 GCC versions, pre-caching the end() iterator of an STL collection before the loop instead of calling it each time as a control condition of the loop made faster debug runtime builds, so I got into the habit of doing that.

In the optimised (O2/O3) builds the compiler effectively did that optimisation anyway, but not at O0.

It meant loop code in the source was longer, but made measurably (~10% if I remember correctly) faster debug builds on code which did a lot of vector iterating.

I have also noticed that often some of debug builds' slowness is actually due to asserts being on in debug builds as opposed to optimised builds, at least in some of the code I work on (which in some cases makes very heavy use of them) - removing asserts can in some cases bring things back to debug builds being ~5x slower than optimised compared to ~30x which is more acceptable.