Lately I've had incidents where web pages are loading so slowly they time out. I reboot my router and modem and instantly the problem is solved.

I'm mostly just curious -- why would a modem need rebooting? Is it that complex a device?

Depending on the hardware, some connections (by default) will negotiate their connection speed based on signal quality over time.

Both modems and routers are subject to throttling. Resetting the connection just starts off fresh.

I never turn my router (or Modem) off - it runs 24 hours a day (behind a firewall of course). I probably boot them once a month or so.

Edit -

One of the specific issues with one of my own routers is heat (it's a WRT600N, known to heat up a bit). Bouncing it doesn't fix the heat problem directly, but it does clear out the garbage that accumulates because of it.

There are some possible reasons in this thread
http://tech.slashdot.org/article.pl?sid=08/07/12/2322213

Here's one quote from a network tech:

Thanks! I don't think heat is part of the problem. If it were, the exterior of the router would actually feel warm, right?

Lots of good stuff in that link too!

It would (mine is always warm to the touch).