It's a part of DPS lag. It's the servers catching up.
If you TWF Chaosblades like my rogue does at the moment in Part 1 you can tell how bad the DPS lag is. Next time I'm in there I might fraps it to show you.
But basically this is what happens. You can see the +1 Repairs scrolling across the screen at a normal pace. But then once I move away from the portal they rapidly scroll the screen till I get over to another portal and start hitting it. Once at the next portal it will go back to scrolling at a normal pace and stacks up the ones that didn't show before I'd assume. Since after all the portals are done the +1's sometimes spam all the way to the chest and once I open it.