The screensaver client is much slower than the CLI and GUI clients, not so much because of the graphics, but because it doesn't get to run in the background all of the time and take advantage of the majority of the time where you're just typing something and 90% of the CPU capacity is being "wasted."
If you want to do so, I would recommend that you use the GUI client; it will run in the system tray while you work, getting extra cycles here and there when it can at the lowest priority; when you want to walk away from your computer, simply bring it up and maximize it. Ergo, you have the best of both worlds: maximum efficiency while you work (it performs about the same as the command line client while minimized), and pretty graphics whenever you're away.
BTW, nice case mod. What kind of LCD is that? Is it your primary monitor (I'd suppose that you'd only do that if this were a server that you just wanted to check on occasionally), or do you run it as a duplicate of some other monitor that is also attached to the system?