Performance Issue with Large Number of Pages (2000 )

It may have something to do with your permalink structure.

http://digwp.com/2011/06/dont-use-postname/

I believe that they recommend setting your permalink structure to start with a number like date based or even %post_id%.

Is this still an issue with the latest ver of WP?

I believe that they have already found a solution to the permalink issue and that it will be included in one of the upcoming updates. I could be mistaken, I just remember reading that somewhere.

Oh, on that same site.

Andrew Nacin said on June 23, 2011:

Well, and to answer a question from above, “Also, what are the chances that WordPress will have a fix for this in a future version?” — the chances are great that we’ll be removing all performance penalties for %postname% in the release of WordPress 3.3, due later this year.

Andrew Nacin said on August 17, 2011:

I just want to confirm that WordPress 3.3 (due in November) will indeed remove all permalink performance issues related to %postname%, %category%, and the like. It’s done and currently in trunk. So look for that in the coming months.

Great news… As someone who uses %postname% permalinks, I’m looking forward to this 🙂

One final questions would be this:
currently the site is returning 500 Server Error, since I can no longer log into the site to change the permalinks, how do I get them changed?

Remove the WordPress permalink rules from your root .htaccess file.

Looks something like this:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

I use my own custom permalink rules, so I’m guess the above is what yours should look like. Just remove them. When you reapply your permalink structure it will rewrite them in (as long as the file is writable).