networking - Why does my Internet slow to a crawl unless I reboot my router every few days?

A few weeks ago, I noticed that my Internet connection had slowed down to a crawl. I waited a few days hoping it would go away on its own, but it didn't get better. So I asked this question about how to make it faster.

The problem went away after I updated to the latest firmware, so I didn't follow up too carefully. But every few days since then, my Internet has slowed down again. Unlike before, all I have to do to fix it is open the router administration page and press the "Reboot" button. Nothing else seems to work, though I'm sure there are options I haven't tried.

If it makes a difference, my girlfriend and I both transfer large amounts of data fairly routinely for school (videoconferencing, downloading entire recorded lectures).

The router is a Cisco/Linksys WRT160N v3 that's about a year old. Most of the time, it deals with just two standard Windows 7 laptops.

The only thing I came across while searching for answers/dupes was this unresolved question, which seems similar superficially, but probably doesn't have the same root issue.

What could be causing these slowdowns, and how can I get rid of them?

EDIT :
After asking this followup question, I installed dd-wrt on my router, and I seem to be getting higher and more consistent speeds. Perhaps more importantly, my memory use is fairly constant. I know this isn't an answer — which is why I'm not posting it as an answer — but it is how I resolved the situation, and hopefully it'll be helpful for someone.

Answer

I'd say that the problem is bad memory management in router firmware. Basically whenever router needs to have lots of connections open, it uses up its RAM, which is normal. When a connection is closed, that RAM should be freed up. It looks like in your case it isn't. As router has less and less RAM available, it becomes slower and slower and in the end you have to reboot it. When it is rebooted, contents of the memory are cleared and you have fresh memory to use.

If that's the case, then there's very little you can do. Your router may be supported by third party firmware like DD-WRT or OpenWRT (where's the rest of its name? I can't tell without it) so you could try installing one of then. Otherwise, you could hope for new version of official firmware which could fix the problem.

To check if I'm right, try opening lots of windows and tabs in your browser and go to as many websites as you can on as many computers as you can. Also, you could try finding a hot torrent and download it. Bittorrent will usually place heavy load on router and if the connection closing problem is there, it will occur quickly.

I had a similar problem on a Netgear FVG318 router and solved it by getting a router which supports OpenWRT. I haven't had any problems since then.