Pretty easy to replicate. Identified rbtray as the culprit using procmon from sysinternals.
Install RBTray and run it.
Open your favorite web browser and go to a page that uses the "browse" button.
Click the browse button. Observe that it takes a longer than expected time to render. Doing this with procmon running will show ~100k reads on rbtray.dll.
Close rbtray. Repeat the test. No slow behavior.