The greatest help for me was always reset my modem. I have noticed two major issues with speed problems:.

1) The first one occures about 2 minutes after I start up LW. I have a system monitoring program and it shows about 2 minutes into running LW, it starts to read the hard drive with 7-8 MB and this of course instantly kills download speed. Have you also noticed that when you first start LW it runs fast, then it speeds drop all the way down, then they start to climb back up again? When I first start it up, for the first two minutes I get 40-50 kbps speed per files even just from 2-3 hosts. Then when the read happens, all downloads go down to 0, then they never recover to more than 10-15 kb/s even from 10+ hosts. If, however I unplug my modem at this point and restart it about 10-15 seconds later, download speeds go back up to high again.

2) Even after modem resets the speed will drop down gradually, this could take about an hour or sometimes even more. At this point, once again, I unplug my modem, then plug it back, the network speed is all reset.

Now, LW does not just affect itself with the slow downs. It affects the entire network, because when LW runs slow, everything else (e-mail, browsers ... etc.) begins to struggle as well. Even when I only download 2-3 files at 10-15 kb/s, everything else is slow. However, after I reset my modem and downloads are back up to 30-50 kb/s, my internet will works fast again. Plus after LW slows down and I quit it, my network speed comes back in a few seconds.

I also tried using another downloading program for testing, downloaded files for about 1/2 hour and it never slowed down, neither did my internet connection ever experienced any drop in speed. My network monitor indicated a full bandwidth use all along.

I still believe there is a glitch in LW somewhere, for no other program causes this slow down.

* My system: G4 dual 533Mhz, 1 Gig RAM, OS 10.3.9, DSL 1.2 Mb/s, LW 4.10.9.

OSX Java is very much to blame here. It's not as efficient as the other Java's. Mac do their own implementations of Java which is the pity. I noticed improvements after upgrading to Tiger & updating Java to 1.5. But that was on my system. Other people didn't notice such a big improvement. But still 1.5 has problems but not quite as bad as 1.4.x

Reducing shares but more importantly keeping incomplete files to a small number makes a major difference to how LW behaves. Having over 2,000 shares is risky on OSX with this issue.