Will my new iPod begin crashing?

Hey everyone. My iPod 4th generation is so slow and laggy. I reboot all the time and yes I've restored it. If I get the new iPod 5th generation and never update it, will it continue to stay fast? I notice the more I updated, the slower my iPod has gotten. Idk if it has to do with the updated apps that are suitable for the latest and fastest technology that Apple has made (iPhone 5s) or what. If you KNOW exactly a lot about what I'm talking about please comment.