I have tried several avenues (and posted a few projects on SL) to avoid having to do this but I've now decided that the best solution to this problem is to rewrite the way wordpress manages it's categories.
The problem as I can understand it with WP and categories is that WP attempts write a WP cache object with all of the categories placed in that object OR/AND maintain a variable with all of the categories ready to be called from such.
In my case with 2.7 million categories this simply does not work efficiently for example: Mysql has to handle a SELECT JOIN on wp_terms and wp_term_taxonomy for 2.7 mill entries with an ORDER BY, all simply to fill a cache object with all of the categories.
I need someone/company who will modify wordpress to handle millions of categories efficiently so I don't have to spend $100's of dollars a month on premium hosting simply because of poorly written category management.
I'm hoping this can be limited to the [url removed, login to view] file in order for the install to still be 'easily' upgradable with future WP releases, but I'm open to any solutions at this point.
Developer will be welcome to develop directly on the current install at Media Temple hosting as the site is still in development. At the end of the project a record of all changed files will need to be provided to me, I don't require the code be exclusively mine or anything like that (you're welcome to sell it on or provide it open source) I just like great quality work.