I recently received an email from my brother with a link to a Daring Fireball post in which John Gruber commented on a blog post by Fraser Speirs on iOS multitasking misconceptions.

Click to view the email

My brother was right. I am obsessive about ridding my multitasking bar of apps I’m no longer using, as I am sure a lot of other users are too. Not only did I think that purging them would help my iPhone battery life, but I thought they were taking up extra, unneeded memory.

The misconception that Speirs discusses at length in his post is that killing the apps on your iDevice is beneficial to the overall productivity and usage of your iDevice. The worst part about this is that we’ve heard this from Apple store employees as well.

I realize a lot of you may have known this already, but this article is for those, like me, who thought that killing apps in the multitasking bar helped preserve memory and, in turn, battery life. This is not the case. As Speirs sums up:

Let me wrap this up by giving you a quick summary:

  • If someone tells you that all the apps in the multitasking bar are running, using up memory or sucking power, they are wrong.
  • When you hit the home button, an app moves from Active to Background and quickly to the Suspended state where it no longer uses CPU time or drains power.
  • An app may request an additional 10 minutes of Background running to complete a big task before becoming Suspended.
  • If memory is becoming scarce, iOS will automatically move Suspended apps into the Not Running state and reclaim their memory.
  • Five classes of apps – audio, GPS, VOIP, Newsstand and accessory apps – and some built-in apps such as Mail may run indefinitely in the background until they complete their task.

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.

Because of the response to his post, Speirs did add a short video to his blog, showing us in real time exactly what he meant.

iOS Multitasking from Fraser Speirs on Vimeo.

So, there you have it. By ridding your device of those apps in the multitasking bar, you’re not improving your iDevice experience at all. Think of it more as a way to view your “app history” (like browser history). However, killing these apps is a great solution if one of them is freezing up — don’t forget that.

I’m certainly not going to be able to stop obsessively killing apps altogether, as it is a part of my OCD behavior and would be hard to change that, but I will definitely be at ease knowing that it doesn’t matter from a performance standpoint.

Did you already know this, or were you just as shocked as I was?