Putting something next to the download doesn't do much given that you could set up your own launcher to do the same thing after download. I wouldn't expect the impact on server resources of a tidy button to be that much if anything - the server appears to spend most of it's time on database interlocking, suggesting there is cpu idle time left over. The impact of saving a write or update, causing the interlocking is the same irrespective of whether a tidy was done on the post.