Acceleroto's blog post about their experience with developing the Pre version of Air Hockey tells the full story:
"Memory management (aka Garbage Collection). WebOS is allows users to run multiple apps at once. Users beg for multitasking. You think it impacts game performance? Absolutely. Even if every app behaves nicely, they all consume memory. Memory management is handled by the OS without any direct say of the individual applications. Whenever the OS decides, it does a Garbage Collection. Currently, this takes about 300ms (about a third of a second). Air Hockey contains specific code to lessen the impact of these pauses, but developers can’t turn them off. A lot of time was spent making sure objects weren’t needlessly allocated to minimize the frequency of the Garbage Collections, but you’ll see the pauses. That may change in the future – we don’t know."
