I have a Droid Maxx, the phone a year older than the Turbo with the almost the same 4.4.4 build, encrypted. You wouldn't notice the difference in performance between it encrypted and unencrypted - it runs just fine. Of course the only difference you notice is on boot up, when you have to unlock the encryption key with your PIN or password, and you must use PIN, password, or NFC unlock methods (the NFC has a PIN or passphrase fallback). Otherwise, there is no discernible difference.