Does it include any nVidia drivers? I had to install Envy with the LTS version and it didn't work well at all. The operating system runs slow as hell, but I manage to just ignore it. I don't know. It automatically loaded the open source ati drivers for me, but I can use the proprietary drivers through the restricted devices manager thingie. If your nVidia card is compatible with nouveau, then those drivers will be loaded and you can load the proprietary drivers through the aforementioned restricted device manager. I don't know what you're doing to get it running slow. It's been responsive for me and I didn't even do any tweaks (yet). Here's a collection of tutorials to tweak ubuntu. Many of those tweaks also work with other distros.