cleaning up auto_increment fields

Hello all! Is it worth my time (both real and processor) to make my application find gaps in the auto_increment sequence (in MySQL) and fill them when I add new data? I'm concerned about overloading the capacities of my datatypes (although they are very liberal). I think it wouldn't be that difficult... but would probably slow the application down... I fear that, because of the relationships I have, if I ever decide to compact the database later, it will be an extremely trying task. Thanks, Ben