When you free a large chunk of memory, it is good practice to return the pages to the system-wide free memory pool with ScavengeMem(), so other tasks can use them:
int32 ScavengeMem( void )
This function finds pages of memory from which no memory is allocated in the task's free memory pool and gives those pages back to the system-wide free memory pool. The function returns the amount of memory that was returned to the system-wide memory pool, in bytes, or it returns 0 if no memory was returned.