I would think that since screens are created and closed, there would be little to no effect in that regards. Normally that takes place on server side... scripts not being called to close or exit and for that you should be able to notice differences in performance fairly easily and there are many tools for . If you are using PHP scripting I would just make sure to clean and exit or sanitize any scripts once they have been called.
"No, you need to use 8080"
I believe you mean using command line via 'telnet <your ROKU ip> 8085' Cheers.