Tag queries really are not the problem. Rather, it's related videos (tags play a part in that). Some of my clients and I have discovered that once you reach about 10,000 videos (local or embedded, doesn't really matter), vShare starts to break down due to the massive amount of time it takes to correlate the related videos. From one site that I manage (has about 20,000 videos), I calculated that for every video that is clicked on, you generate about 400,000 relational queries. On a powerful server, it takes about 20-30 seconds to do. The only solution that I have come up with so far is to remove the related videos code completely out of vShare (out of the functions). Eventually, I'm going to probably rewrite the code or use a different method of gathering related videos.