App runs extremely slowly on resume

[DaveC]

Hey guys, so my game runs perfectly - 60fps for as long as I want to play it, but when I close out of the app and then click back on it the game runs really slow, like half the speed! If I completely exit the app and launch it again it will run full speed again.. this is obviously not acceptable! any ideas what can cause this? how can I find the source of a problem like this? this occurs on my iPhone 4s (actual device). I'm running the latest beta and the latest xcode. I'm not sure how long this has been an issue as it's something I'd never really tested before now.

[Anders]

Hi Dave
We have previously tried to find the cause of this issue but without much luck as it seems to be completely dependent on your game (CPU/GPU wise).
Other users had luck switching on/off vsync and changing some compile-flags.
If you want you can send me your game so I can try profile it. Maybe your game gives a better insight into the cause than previous attempts I did.
We really want to have this bug found so any help is appreciated.

[DaveC]

okay I've been playing around with it a bit more and I found that if I close the game and then Double Tap the home button (to bring up the running/recent apps) and I resume my app via this menu, it works perfectly. BUT if I try to click on the app from the main ios menu, it will always lag at around 40fps. Does this give any clues as to what might cause the problem? I'll play around with v-sync and some other options and if I can't get it working I'll definitely send it to you!!

To clarify - say I run the app, close it and then click on the app icon to resume (in the main iphone screen with all the apps) the game will be running at about half speed. Now if I press home to return to the main iphone screen, then double tap home and click on my apps icon through the app selector at the bottom of the screen, the game will resume at full speed. weird stuff :S

[DaveC]

Okay.. so after more testing I realize this happens on any app I make - no matter what. I made a brand new app with 1 active object and 1 counter for fps.. at first it's at 60 but when I press home and re-open the app it's down to 40. Launching the app from the quick launch (double tapping home) and the game runs at 60fps again. Did you get my email I sent? I suppose it's kind of pointless now anyway.. it can't be anything to do with my apps code/cpu/gpu useage.

Another thing, when I save a new (completely blank) MFA (while the build is set to xcode) the mfa will be around 15mbs in size, if I change the build to exe it will be 300. Now I've alway snoticed that the xcode build mfa is bigger than normal.. but now the smallest I can get it is 15mb..? is that right??

[Anders]

Yes I gor your email, thanks for the file. I'm looking into it

When you set the build-mode to XCode project export it will store the iOS launch images into the MFA file and they can be quite large unfortunately.

[xhedgehogx]

This issue also happens if you're running an iPhone only app on an iPad and change it's size.

But, it's also not only a MMF issue, I've noticed it on other app store apps too.

[DaveC]

I changed my apps resolution to 480x320 and I don't get the problem anymore....... it's so random!?!

[Anders]

It seems very random yes, it is very hard to debug

[paobrasil]

I had this problem playing the game Clash of Clans on iPad3, so this is not a MMF problem