Actually that really isn't there to be funny. I am serious about that (mostly).

This is from painful experience:

If you change something that is broke, only to remain broken or broken in some new way. In general all you hear is FIX IT!

However the pain you will experience if you break something that isn't broken trying to improve performance... Expect to be burned at the stake. Don't be surprised if costs you your job.

Now incorporating these changes in a build for something else that is broken if tested VERY throughly is an option.

Complaints come from many sources. A stable system is a good goal too. Performance is also a goal. If you haven't noticed before a high performance system is almost always less stable than one that performs just a little less optimal.