Inactive RAM - Not Returning to Free

Question

I have come to notice that after launching somewhat memory hungry programs, such as HandBrake (a DVD ripping application), the RAM is slowly activated until there is at least 1 GB Inactive RAM, even though actual active and wired RAM is 1/2 GB at most.
Though this is to be expected, it seems that RAM continues to move to Inactive until there is only 50 MB of Free RAM left, even though no more RAM is being used for the actually application.
You would think this wouldn't cause a difference in performance, but all streaming video moves with short blips every half second, and in general the computer begins to lag.
Yet after I terminate the application, none of the RAM is restored to the Free state, and the lag continues, suggesting that the computer is digging to the actual Hard Drive for memory.
Does anyone know what is going on, or any pointers on how to avoid this?

Answer 1

Hi,
There are some changes to memory garbage collection introduced with Leopard. Of course, there is supposed to be improvement. Here's an article I found:
http://developer.apple.com/leopard/overview/objectivec2.html
It could be an older application might not be optimized for best garbage collection strategy, and the default under Leopard might not be as efficient. A tweak and recompile might be needed to specify the best suited garbage collection alogorithm. This is the kind of thing that probably wouldn't show unless an application allocates and deallocates a lot of memory. It sounds like Leopard holds off rebuilding its free list as long as possible, so there's more work for it to do and hence a video stutter.
I think for something like VLC, the generational garbage collection strategy may get in the way because moderate chunks of memory are getting allocated at a constant rate as rendering takes place. The garbage collector thread of a Cocoa application runs at low priority and the way allocations are taking place make more work when the collection thread has to examine the object graph for long-lived objects to free. I'm not a heavy duty kernel and Cocoa person; please forgive me if I am in error.
The upshot is that Leopard may be the cause, but not because Leopard is doing something wrong per se.
Bill