Still with my mind preoccupied with what I had to take care of on Monday, I went through my run-up and checklist, lined up on the runway, brakes on, full throttle, tweaking the mixture then starting my takeoff roll. I was instrument rated with about 1,500 hours in this airplane, which I had owned since new and was the only pilot, so I was well experienced and comfortable in it and knew every nuance, squeak or rattle by its first name. I had perhaps not rolled 100 feet and it "felt wrong," and right then I should have shut down but the urge to "get home" overrode good judgment. The airplane just did not seem to be accelerating as it should. My "justification" to continue was that it would pick up speed, especially as I had a "downhill" slope coming up; all the time the feeling of "something's not right" was gnawing at me. When I reached the crown I barely had 40 knots, normally I would be at 55 to 60 by this stage; still I kept going and the end of the runway kept coming and I was nowhere near having my 75 to 80 knots.