Why iOS5 is Affects Battery Performance

I’ve had this conversation IRL about 5x in the last 3 days, which means I should mark it here. Basically, if you’ve noticed iPhone battery performance slipping after upgrading to iOS5, here’s why:

• You may be on an older phone (3G, 3Gs) that simply can’t handle the new software load.
• Every app you use is now authorized to grab your persistant location. This definitely strains the battery. Simply go into “Location Services” in settings in turn off 95% of your apps that want your location. For instance, there’s little reason for Angry Birds to know your location.
• In the “Notifications” bar, they’ve defaulted all of your apps to be in the bar. That includes things you may not need (like stock ticker, for example) as well as weather, which grabs location. The notifications bar is trying to pull data more often to update its scroll and, in the process, is again using the GPS sensor which kills the battery.
• My sense is that iOS5 also converted lots of mail clients to push/fetch from pull, which also makes the phone communicate more with servers, of course draining more battery. Set these back to manually “pull” if you check your iPhone habitually like I do.

Any other tips out there to preserve battery in iOS5, aside from screen brightness?