Hello tolstoy

When LW has been inactive for a while (as far as searches are concerned), the extra ultrapeers are dropped since they aren't needed for file transfers. One UP is used to keep you connected to the network.

As soon as it looks like you are going to need a search, the extra ultrapeers are added in preparation.

So, when you've been away from the screen for a bit, you'll notice the connection quality coming back up to full readiness.

That's one explanation of what you may be seeing.

As far as times of the day, the network does fluctuate. See here for details http://www.limewire.com/english/content/netsize.shtml

Another real possibility is that your ISP automatically controls p2p packets (bandwidth shaping) at peak times. You'll have to dig at their help desk to get a straight answer to that question

Cheers