Hey Paladinleeds (mind if I just call you "Pal"?)
Well then, I would like to call you out on calling me out
... well, kind of anyway...
Everything you say is absolutely correct, but we aren't referring to the same kind of background processing! What I'm referring to are background tasks that run constantly in the background for undefined periods of time. For example, pressing the windows-button while running ND7.5 (Nokia Drive for WP7.5) will put ND into a dormant state. Navigating back to ND will wake it up, after which ND must reestablish a GPS fix and then carry on from there. ND8.0 won't do that... it won't switch into that dormant state... instead, it will keep tracking your location in the background the entire time. This is an example of background location/GPS which I mentioned, but the same works for background audio and background VOIP.
What you are referring to is called scheduled background tasks. These are restricted to running no longer than 25 seconds (usually much less). This is what weather apps typically use to keep their information up-to-date. The good news is they won't noticeably slow down your device, as 99.99% of the time they won't be running at all. I'm assuming this is the approach the HTC Hub will take, but of course I could be wrong. Anyway, it would seem rather crazy for the HTC Hub to constantly track our location (every step) just to get up-to-date weather information. Normally, the weather 20 feet ahead isn't that much different
That is what I meant when I said:
"Unless HTC is using any of these features in their Hub (extremely unlikely), you won't notice any performance difference whether the Hub is installed or not."
This is an overview of the different types of background processing WP supports. Note that none of them are "real" multitasking, as they are all intentionally constrained (in one way or another) in order to extend battery life.