Raj,

besides the remarks of Peter, which should be considered before first, I would (if it is still too slow) implement a binary search. It is a lot faster and more scalable than a linear search. But again, if it takes 5-6 seconds to search through 512 bytes, then something is fundamentally wrong, and it is most likely not related to your search method.

Maybe you should verify your read routine and measure the time it takes to do a sequential read of all locations in serial memory.That should give you an indication if its your search algorithm or your read-routine that is having a problem.

regards
Patrick