Like Ibai said, I also grow them in DMEM+10% FBS. What do you mean by slow? When I split a confluent plate 1:5, it will usually take 4-5 days to be confluent again. Are your cells clean? Mycoplasma can affect cell growth...
you can grow this cells in DMEM (high glucose), 10% fetal bovine serum (FBS), 0.1 mM , MEM Non EssentialAmino Acids (NEAA), 2 mM L-glutamine, 1% Pen-Strep .
also i agree with Richard Marcotte , this cells take 4-5 days to be confluent again .