A slow clothes dryer usually means it's time to do a little maintenance. In any case, it makes good energy sense to give your dryer a tune-up about once a year.
Unplug your dryer and disconnect the exhaust hose at the back. Clean it thoroughly. While you're at it, trim the hose so it's just long enough to pull the dryer out from the wall about three feet. You can save up to $25 a year in energy costs this way.
Consulting the dryer's service manual, open the access panels and vacuum out all the lint. Examine the lint screen for any damage. If you're using dryer sheets, you'll probably need to scrub the screen with a toothbrush and soapy water. Yes, the nasty chemical buildup on the screen is also in your clothes.
Finally, be sure your dryer is level and stable as you replace it. Done!