It's basically that. Modern OS's including MS or *nix have pretty smart garbage collection routines, but nothing is immune. DS clearly has internal memory management issues, but the OS isn't aware of what's no longer in use. From the WIDE variety of anecdotes I've heard on this, I can only assume that there are some magical amounts of free RAM where the game manages things correctly, and other maybe arbitrary amounts that it miscalculates what it can do w the RAM it's been allocated. At times it's hard to tell which way to go to improve the situation. If your phone has a small amount of installed RAM try a booster app or otherwise try to free up RAM. If you phone has lots of stock RAM try running more stuff, like a screencap app, before launching DS. If the obvious direction doesn't work, try the opposite. Seriously. Also check out that you have ample storage space. If DS is choking on a restricted cache it will have similar symptoms. Good luck. Who is affected most seems to change every update. Maybe the next one will be better for you.