Jailbreak or not? Please help?

[WheatiesXD]

Okay so here's the deal. I had jailbroken my first ipod touch. I was an "ipod n00b" and I would rarely restart my ipod. I would open up lots of apps, install and uninstall all the time and whatever. And I didn't restart it much, like I said before. One question I have is: Can certain apps still be running in the background on a jailbroken ipod? I'm only asking because my ipod became very laggy and I would have to restore it every so often. I kept doing this for a while until I gave up. Soon after this I updated to 2.0 and I know it's supposed to take a while to update from 1.1.5 to 2.0 but it felt way too long. Also, sometimes it would take up to 5 minutes to reboot, even after the first reboot after 2.0 update. I got fed up and took it to the apple store (they saw no signs of a jailbreak) and they ended up giving me a new one. Now, I've had this new ipod since around the time of the 2.0 release. It's been good and I've been wanting to jailbreak it but idk if its worth it or not. Any tips or reasons to jailbreak better would be appreciated. I just don't want anything like this happening again. I know if I did jailbreak my new ipod I would reboot it more often.