Why should someone disable the compiler-optimization

Question

a coworker, who doesnt work here anymore, disabled the code-optimization of one of our projects some time ago. There is no way I can contact him anymore and looking at the changes he made with his commit I cannot see any reason as to why he did that.

Our program has some great bottlenecks and even though I am not sure if enabling this option again would bring any boost in performance, I would say its the better way to go..

The main problem here is that we would have to check every bit of this badly-written software for any side-effects which could take literal months to do..

My question here is if there are any reasons known as to why someone should deactivate this option and for what reason?

Answer 1

When debugging with that option turned on, some variables can't be inspected as their lifetime has been minimized. It is very likely he deactivated it to be able to debug more comfortably. There should be no effect on runtime apart from a slight slow down.

You can always try to check on a non-production environment if reactivating it helps with the bottlenecks you mention. That being said, do not expect any major speed-up.