We cannot possibly answer your query with the scant information you've posted. You haven't even told us what make and model TV you are referring to. I suggest you visit the TV maker's website for technical info on that model.
You could attach the largest drive you wanted to the weakest of rigs and it would still access it fine. Storage performance wont be affected by your TV's processing capabilities. Did a salesman give you this advice?
What your issue is going to be is if the TV in question can read the NTFS file format your going to need to use on a drive of that size. Most TV's and home theater devices (including current-gen consoles) can only read FAT32 which is typically used on lower capacity flash drives.