The fact that your computer is (apparently) at the minimum spec to run the game is not Cryptic's fault, nor is it something they should "fix". Invest some money into a better computer (or internet connection, if you have low-speed DSL) and stop complaining.
Cryptic has no control over what you use to play the game, but they DO say, plain as day, what the requirements are, and what they RECOMMEND you use as a minimum.
I'm sorry, but my computer makes most people's machine look like a toaster, and I have this problem as well during peak times. Really late night isn't bad, prime time I don't bother.