bear in mind that L7 will look for the specified patterns in ALL connections that hit those rules. you should make sure only unknown traffic reaches those rules, and then limit the number of L7 rules as much as possible - this is regex we are talking about, it takes a lot of resources to scan everything ...
Returning to the question: Is the cpu usage of each pattern similar to those of the l7filter ?
Asking cause it's nice to know, from someone from inside.
One could try to avoid using high cpu usage filters. And it could be nice to know what are you doing before actually doing it, it's kind of risky to put in traffic a job that you can't thoroughly test by your own, with one or two machines making the traffic.
Tx in advance.