Comment by Thorrez

I don't know what you mean by "DFA's can't backtrack". Maybe you mean DFAs don't support backreferences, which is true, but NFAs don't support backreferences either.

I believe if r is the size of the regex and d is the size of the data, an NFA is O(r) to compile and O(rd) to execute, while a DFA is O(2^r) to compile and O(d) to execute. So DFAs are slower to compile, but faster to execute.