The problem is that the clothes don't really tumble, pushing hot air around and through the fabric, but instead just basically rotate. This isn't how a tumble dryer is supposed to work.
So the idea came to me to get some of those dryer balls to try to help the clothes tumble properly. I checked amazon and wasn't really too thrilled with what I saw: lots of hollow spiky balls that people complained tended to lose their spikes. After a bit more searching I found some felted wool balls that looked a bit better, but for $30 for a six pack they didn't really inspire me to buy.
Then I thought to myself "I'm a man, I have a perfectly good set of balls I can use", specifically the set of lacrosse balls that I bought a few years back for juggling. They're nice and heavy, rubber, and Canadian, the three qualities that matter the most.
I gave them a try last night, and they seemed to work quite well. The load came out dry after about an hour of drying rather than coming out with damp spots after 2 hours. I'm not sure if they'd make much of a difference in a dryer that isn't painfully undersized, but if you find yourself disappointed with your drying performance, you can do worse than taking a chance on using your balls.