To test in best faith you could follow through: Run the unit tests. Log in as an admin, ensure theme designer mode is off and then purge your caches. Using Firefox/Chrome/Safari browse around the site and check things look as expected. Repeat for a couple of themes including standard, and clean. Switch to IE browse around the site and check things look as expected. Repeat for the same themes as above. Open lib/csslib.php in an editor. Search for the use of css_chunk_by_selector_count within css_store_css and make its third arg 1500. Save the change. Using IE log in as an admin and purge your caches. Inspect the CSS loaded once the redirecting is finished. Check that the style sheets that the import statements within the first three CSS sheets contain either "/_s/" or "svg=0"