Lol....sorry for this, but for a start i'd stop usin Fender strings. I doubt if its anything to do with your problem, i used to use them and just don't like them.

This bit's probably more relevant. I now own a seven-string, and while it is marginally harder because of the thickness of the string, it all depends on the person. The only real reason i think mine is a bit slower to play is because the action has to be a little higher than i'd like to prevent fretbuzz on my low B.

My advice is if you like the weight of those strings better, stick with it and your speed will improve anyway.