Help a new guy out. Seems sluggish all of a sudden...

I've had my hero for 3 or 4 days now. I understand that i do not need a task manager to shut-down apps, but don't fully understand how this works, since apps like Pandora (music streaming) and sportypal (gps tracking) continue to run in the "background."

Adding to my confusion is the fact that I'm noticing the phone get sluggish lately, even after a fresh reboot, with only two programs running (Pandora and sportypal). The past 3 days, there were no problems, but now I cannot run with music because the music continues to skip - and pandora becomes unresponsive.

I thought perhaps there were too many apps (I've downloaded about a dozen apps) and so I uninstalled most of them. No better.

What, if anything, am I missing? Can I be low on space or memory, or what?

Thanks,
Pete