Well I am almost certain you have seen and tried my tutorial, But in case you have not tried recently it is located here;
https://www.mpgh.net/forum/287-crossf...ucing-lag.html
Also remember some Systems are just not naturally good with handling games.
Example; I follow all tutorials , Including my own and can not go above 10 FPS. This is not because the advice isn't working, But because my System sucks. xD