Depends on where you have the footage stored and the format of your HD Footage.
If you have the footage on the internal drive of your laptop.. then you're gonna have trouble.
If your footage is on a FW400 or USB drive, you're gonna have trouble.
If you footage is uncompressed you're gonna have trouble.
If you have your footage on a FW800 drive, but the drive is almost full, you're gonna have trouble.
What format is the footage, and where do you have it stored?
If you primarily work with HD footage on a macbook pro I would recommend to work in ProRes 422, get an express34 e-Sata card and a fast drive like the G-RAID (as long as you have a MBP with the express slot, if not then go with FW800 drives - the G-RAID has this connection as well)