27,000 is a lot of items for a drop down list. I would suggest you use a popup window with a list view instead.
As I said, 27000 addresses open almost instantly when I recreated the process in a new database. I also have the "Auto-Complete Using Value List" selected with the Drop-Down menu so I can pretty quickly jump to all the addresses with the number 1234 by simply typing 1234 then using the down arrow to find the exact 1234 + street name or continue typing to narrow ther search even further.
The Auto-Complete doesn't appear to be available with the pop-up Menu and further it appears I have to click on the arrow at the bottom of the pop-up menu to scroll down the list. That takes way too much time.