I may sound like broken record for saying this since it is common advice, but it's good advice so I just have to ask. What is your specific performance issue with the if statement in question, and what profiler data do you have to back up that assertion?

Many optimization problems over which people agonize, plan, and scheme aren't really problems at all. If serialization is important, I can't imagine what performance degradation a simple conditional is causing that would be worth a bunch of extra code to do the serialization. I could see that degradation in a hot spot of the code, though, if a profiler actually showed it.