Drawbacks of repeating a single pattern matching procedure for many patterns
One common way of solving pattern matching problems is compiling a DFA that matches the pattern. If you have several patterns in mind, you can combine all of them into a single DFA, which will match all of them with a single pass, rather than one pass per pattern. On the flip side, the DFA could have many states and so might not fit into cache, which would cause a performance hit.