iOS 7 on iPhone 4S not backgrounding / multitasking properly

I've seen this posted in the iPad forums but wanted to post here as well -- see these posts:

https://discussions.apple.com/thread/5432258

https://discussions.apple.com/thread/5404451

It's like the phone has completely lost the ability to multitask. Nearly any time I switch between apps (let's say from Safari to Facebook), when I switch back, the app seems to refresh/reload/launch from scratch.

Examples:

• Facebook/Maps - get halfway through typing a message in Facebook, check Maps, come back to Facebook, and the Facebook app reloads and the message text I typed is gone
• Safari/Gmail - get halfway through checking in to a flight on a Safari webpage, check Gmail to get confirmation code, come back and Safari reloads page

Same thing if you're reading a document - switch away, come back, and the document refreshes from the top and you lose your place.

Extremely frustrating! I pulled out my old iPhone 3GS on iOS 6 and could do the same tasks with proper multitask / background operation as you would expect -- so I don't get why the iPhone 4S can't do it. I know that the iOS 7 probably needs a lot more memory than iOS 6, and the iPhone 4S has half the memory of the 5 and 5S, but for real, this is incredibly annoying.