…at least to some degree. Well, there are human conditions that distort the perception of time but it’s highly unlikely that you’re one of them. So you are a performance tester too.
The biggest annoyance for a performance tester is to get code into a performance environment that CLEARLY has issues that can be detected by the simplest means available (well.. second most annoying, as finding obvious functional defects is even worse). This is where you as a (whatever kind of) tester come in.
You know the times you drum your fingers on the desk waiting for that spinning wheel in the browser to come back? The batch job where the execution is exactly “making one cup of coffee” long? The usual response from you would be to shrug and say something like “This is just the environment. It’s system test afterall.” or “Let performance testing take care of it”.
Now, I can totally relate to such sentiments! We’re all busy and have deadlines to meet. I’d make the case though that you’d actually help the project as a whole and thereby yourself too by not ignoring such issues.