Customize existing WordPress plugin (Advanced Custom Fields)

We're using a plugin called Advanced Custom Fields in our WordPress installation for Bloggingheads.tv. After recently migrating our data (about 9000 records) from our old CMS to WordPress, the whole WP admin area has slowed down to a crawl whenever we open a record that contains custom fields. You can read other people's remarks about this slowdown problem here: [login to view URL] We use ACF's "relationship" field type to link posts, and strongly suspect that the slowdown stems from the lookups required by the linkages. We think we have isolated the source of the problem to the loop at Line 379 of the plugin's /core/fields/[login to view URL] file, which creates a JavaScript picker box of items linked to the current one by the relationship field. We need to maintain the ability to link to related records while creating or editing a post, but hope there is a way to do it without loading so much data.