Registers aren't free; of course turning on frame pointer elision is going to give you a few extra percentage points of performance. The problem is that it will interfere with your performance team's ability to further profile the program and triage crashes, which is very, very likely going to be worse in the long run than the savings you get from this particular optimization. On register-starved environments like x86 (like the one you linked) it's somewhat forgivable but on any modern platform it's a bad tradeoff 99.9% of the time.
