One of the many improvements in WordPress 2.7 is the updated configuration of the visual editor, TinyMCE. It was optimized to support caching better and to load faster.

The compression whitin WordPress is gone and all editor components are included as standard Javascript, CSS and HTML files. However a lot of servers compress these files automatically. If your server doesn’t do that, the first loading of the write/edit page will be slower, but after that the editor loads a lot faster than before, as all files are in the browser’s cache on the hard disk. And if the “Turbo” is turned on in WordPress and Gears enabled, the speed increase is even bigger as the browser does not have to check if any file has been updated.

In my (non-scientific) tests the loading time of the Add New Post screen went from about 5 – 8 sec. to about 1 – 2 sec. depending on the Internet connection and the computer speed.

The removal of the compression whitin WordPress also improves compatibility with some unusual server configurations and fixes some hard to catch errors, for example when there are php errors or output starts in the current theme’s functions.php file.

Currently the editor’s settings together with all Javascript files are included directly in the HTML head section of the page, making it a lot easier to troubleshoot.

There are a few steps that would help with the troubleshooting if the editor doesn’t start or work properly:

1. Make sure the “Disable the visual editor when writing” checkbox in your profile is not selected.
2. Whitelist or set your blog as “trusted” in your firewall and antivirus program.
3. Disable Gears, clear your browser’s cache, quit it, start it again, go back to the write page and force-reload it several times, while holding down Shift (Firefox) or Ctrl (IE). In Safari select Clear Cache (from the Safari menu on Mac).
4. Try another browser and/or another computer.
5. Disable all plugins, clear the cache, restart the browser and try again.
6. Delete both wp-admin and wp-includes directories and upload fresh copies from the WordPress installation package.
7. And finally install Firefox or Opera, note any Javascript errors, especially the first one and try searching on the support forum for a solution. If no solution exists, open a new thread including the error.