Adding tags can cause the browser to freeze up while attempting to display the suggestions drop-down

Steps to reproduce:
1. Google Chrome 20 on Linux x86_64 (Ubuntu 12.04)...
2. XWiki 4.1.2
3. On any page, click the "[+ Tags]" at the bottom of the page.
4. Add a new tag and save.
5. Click on another page and type the same tag, but continue quickly and add a comma and try to type a second tag without waiting for the drop-down.
6. The browser will typically freeze if you do not wait long enough for the drop-down to appear and be populated.