As old items build up in the queue, it can consume large amounts of memory.
To remove successful transfers from the queue automatically
On the main menu, click Tools > Global Options (or press ALT+F7).
Expand the Transfer node, then click Events. The Events options appear.
Select the Remove successful transfer items from the queue automatically check box to erase items from the queue after they have transferred. Clear the check box to keep items in the queue even after they have transferred.
Click Apply if you are going to make changes to other pages; click OK to save changes and close the Global Options dialog box.