If I were you I'd get some core code working drawing lines and points. Then I'd insert delays to see how slowly I can get away with working to get a visually acceptable result - not less than 25Hz refresh rates. That gives me the time window I have to work in to accomplish other tasks. Now you don't need to check for user input ever 1usec, or every 1000, but every 200,000 so that won't be a problem. Apart from the display, only the userinput response time will be noticeable.

Steve