emacs24 on mac cursor movement is quite slow

Recently I began to use Emacs on Mac OS instead of Ubuntu, but one thing annoys me so much is that cursor movement is much slower than that in Ubuntu. Specifically, when I use c-n, c-b, c-f, c-p, the cursor moves slow, any idea about this issue? Btw, both the separate gnu emacs 24 and start emacs within terminal have the same issue.