EasyDiscuss Performance - issues and suggestions

We have a large forum (170,000 posts) which we have migrated from phpBB - we love the functionality of EasyDiscuss but have come up against some performance issues:

1. We are getting white pages every few hours caused by the Joomla cache running out of memory (over 130MB) - there are only a few hundred files in the cache and non-directly related to EasyDiscuss that I can see but the issue started when we installed EasyDiscuss. Clearing the cache allows the site to run again. Any insights you may have from other elarge EasyDiscuss installations would be gratefully received

2. You have a database query error in models/posts.php - you are using TIMEDIFF when the different can be over 838 hours. This throws a MYSQL error message. Instead of using the call like

TIMEDIFF(T1,T2)

you should use

TIMESTAMPDIFF(HOUR, T1, T2)

3. Your method getDiscussions generates a VERY slow query on our server - over 0.7 seconds. More than 0.2 seconds of this is to calculate last_user_anonymous - which is not needed on our site since we don't allow anonymous posting. Please add a check to the config before adding this sub-query

4. Your method getDiscussions also seems inefficient in linking in the post type data for some reason. This could easily be found using PHP and a lookup to a cached data call. When I remove the anonymous and post type parts of this query it takes 0.3 seconds instead of 0.7!!

Thanks

p.s. How do I change the domain for EasyDiscuss from our development server (ubu.jeventsclone.net) to the live server (http://www.jevents.net)?