...and we upload a lot of files so... its slow frequently.
What I Know and How I Know It
I've added some seconds logging for various processes on shift-click. I used two machines simultaneously. No one else was logged in and no server-side processes were running. I loaded my list view once and it took ~10 seconds (its a big intense list with a lot going on). Then, I simultaneously selected a file for upload AND load the exact same list view. It then took about 80 seconds. (I used a 300 MB file for that test but we never upload files quite that big.) I've now accomplished about 2 dozen similar iterations. The slowdowns occur even for small files.