The largest difference in performance between a VPS and a dedicated box is Disk I/O (much better on the dedicated). Given that, I think it's unlikely that just

The largest difference in performance between a VPS and a dedicated box is Disk I/O (much better on the dedicated). Given that, I think it's unlikely that just switching to a dedicated box would help significantly. A useful baseline might be to use YSlow to compare how long it takes to load your page in Rails vs. a static version of the same.