[Mashiro]

I don't think that you would experience such issues. However I cannot answer this question properly for 100%. I usually installed PHP memcached but never configured it or anything. It would use default values. So I never made the experience with memcached installed vs memcached not installed. Depending on what you host the difference might be small or barely noticable (also depends a lot on how much power your server has). I never experience the issues you are worried about though.