updating a lot of UD Text# fields is taking forever, what is a faster way?

The one thing that comes to mind is a UD dim with 27,000+ (and growing?) members.  If you have just 10 more members in any other UDs, you're pushing the optimal Data Unit size before even thinking about how many accounts you have.

Have you considered keeping these projects in a SQL table created in the application database and using a hybrid approach?

If you want to post your code we might bable to provide extra eyes to help optimize your code.  The performance difference between passing byref and byval at the current number of iterations will be almost imperceptible.