Android: performance increase of the app after 15s-120s. Why?

Question

I have a bit of a problem with a game I am working on. The game runs very well on most devices, except Samsung Tab and Galaxy S (it could be more, but I have reports about those two).

What happens on those devices is that the app appear extremely sluggish for 15s-120s then speeds up dramatically (from 5fs to 30fps, which is the normal performance elsewhere). This seems to happen only when the game is installed (or reinstalled).

What could cause that problem?

• On the first run, we create a couple of files on the SD card to store settings, but I doubt that could have a lasting effect?
• The JIT takes a whiles to kick in? But it runs perfectly fine on other platform with and without the JIT. Admitedly, by disabling the JIT, it appears that the slowdown will last longer on the Tab, so there may be an effect.
• Could it be that the device tries to rearrange out the objects are laid out in memory? The game does take quite a bit of space in memory.
• Is there any known problem with Samsung devices? (It appears to be a problem on those only)

Any help is welcome.

Answer 1

You could try to call dalvik.system.VMRuntime.getRuntime().setMinimumHeapSize() early in your app with about the size of the heap while your game runs. This will allocate the target heap size at once and avoid reallocs.

I know it is deprecated but who cares if it helps.