Hello I know i've been here since '09 but im still no computer wiz. There's probably thousands of topics about this but this ones special in a way

I go into one of the new sx tracks everything's going nice and smooth until I get passed the first lap then whenever im on the ground it gets all weird and it like slows down then speeds up a lot, when I jump its nice and smooth. I go to last years tracks or any other older track it doesn't do this at all. I haven't tried much because I don't want to mess anything up.
This might not be MXS related at all but my laptop now overheats whenever I play a game for a long period of time say for a hr and a half of MXS it will shut down automatically, happened a couple nights ago only once and I know its not good so what should I do about that? Time for a new laptop? I have a HP Pavilion dv6 Notebook PC. About 4 years old.
If anybody knows a solution to any of these problems please reply!

Thanks