Fraser Spears has published two posts detailing how multitasking and iOS works.
Most people (including myself believe)
All those apps in the multitasking bar on your iOS device are currently active and slowing it down, filling the device's memory or using up your battery. To maximise performance and battery life, you should kill them all manually.
Fraser summarizes by saying
Put simply: you do not have to manage background tasks on iOS. The system handles almost every case for you and well written audio, GPS, VOIP, Newsstand and accessory apps will handle the rest.Here's my personal experience: On my iPad 1 the memory management is terrible. After using my typical 8 or so apps for about 30 minutes I see a noticable slowdown in processor speed and memory. I get a lot of crashes when using Twitter and Flipboard. To combat this, I purchased an app called System Activity Monitor, which in part kills all open apps and frees memory. If iOS perfectly manages the backgrounding of apps and memory why is this happening to me and why does System Activity Monitor help so much?
Fraser summarizes his most recent post by writing:
If I can summarise my point: killing apps manually is fine as a troubleshooting step but it shouldn't be part of your daily routine.Well, I summarize by writing that if I wait until the memory usage is visibly sluggish and then kill the apps by double clicking the home screen and then cleaning the rest of memory with System Activity Monitor, the device returns to it's perfectly usable state.
In this picture I have 16 "open" or "recently used" apps in the background and the phone is noticeably sluggish and I launch System Activity Monitor. Note the Free Runtime Memory when these apps are "naturally backgrounded".
The apps are:
Air Video
Messages
Diptic
Photos
Music
Camera+
Camera
VirtualWallet
Phone
Calendar
In this shot, after about 10 seconds System Activity Monitor has done it's thing and freed up about 300+ MB of space. Back to normal.
What say you? Why is my experience so different from Fraser's?