The Home section of every newspaper occasionally warns readers to clean out the lint trap on the clothes dryer: resulting in reduced fire hazard and faster clothes drying. My dryer seemed to be taking forever with large loads so I went the next step: disassembling all exhaust vent duct segments and washing them out with a garden hose – one disgusting tube at a time.
I knew the duct work had been there for at least 15 years but was still surprised at the amount of glop that washed out (as pictured) and by one nearly-complete plug of lint I found.

Just above where the flexible steel vent is duct taped (it's really always been duct, not "duck" tape) to the rigid sheet metal tube above it, condensed lint had narrowed the cross section to perhaps half of what it had been. That's why the dryer had been so inefficient.

There was another big wet glop in the tube just to the left of the elbow. As exhaust air turned the corner it became more turbulent, creating a deposition zone.

Further on down the tube there was a quarter inch uniform layer of damp lint. It got there because the basement is cool, especially when the HVAC air handler is on in the summer time. Water condensed on the inside, gradually trapping lint in increasing thickness as the years passed.

If you had a dryer in a cool back porch room the same thing would happen over time, even without home air conditioning.

Anyhow, the heavy load of wet towels and blankets that used to take 90 minutes to dry now only needs 25.

I'm probably saving a very large amount of energy and money, from now on in. Especially since our electricity rates just went up 40% due to energy "de-regulation" rules promulgated during the last Clinton term: a law which, thankfully, did the exact opposite as the Republican Congress and the Clinton Administration claimed it would!

Bottom line.

Dryers are very energy intensive appliances. It does little good to have an ultra efficient washing machine if the dryer tubes are plugged. If you live in an apartment and pay your own utilities, the same holds true. Clean out the lint filter and every so often the vent ducts.