Originally Posted by ray_smuckles

Not sure if this will help with your situation, but I found an app in the marketplace called "Super SMS Quick Delete" (developer name is Superdroid.net) that has worked well for deleting lots of texts. You can delete entire conversations at the top level, or (this is why I got it) it allows you to go into a conversation and place check marks on all the messages you want to get rid of and then remove them all with a single press of the "delete" button (as opposed to having to delete them all one by one). It also has a "select all" button to quickly check mark all messages within the conversation.

It is pretty simple and seems like a relatively light-weight app. All it does is delete, so maybe it would have an easier time handling the massive amount of texts you are dealing with. Hope it helps.