1. Clear your cache regularly. I sometimes find that Google will cache the scripts and if you are using old ones; it can slow down Google. I will run into the 'there is a new version of the UI - please refresh the page' 20 times in a row; and clearing the cache usually fixes this.
2. Look at how many rows you are examining. If you are using 10 rows; its often fast. If you are showing 100 or 500 rows; its often much slower. So, deciding how much data you really need to see can speed up the UI as well. If you are doing most of your work in the adwords editor, often you can use just 10 rows in the UI for navigational purpose, then switch to a larger number on the pages where you want to see that much data; then switch back to 10 rows.
3. Look at all the data you are displaying. Google has to retrieve all the data to show on a page. So, if there are columns you never use but are being displayed, feel free to remove those from the UI.