LW disrupts everything!

Running OS 9.1 on a 9600 299Hz G3 upgrade 256M RAM...
LW starts fine, search all right, DLs all right (though easely losing sources, 7 to 1 makes a difference...). BUT: after about 20 minutes, the traffic light turns to red and I need to reboot to get internet back on. Guess it might be lagging my connection, maybe.
It used to be real itchy but I did the enable javamachine trick (don't remember the name precisely) and it got much more speedy, responsive and all athn it had ever been, even getting rid of shared libraries made unavailable to other programs (even finder -> 3-finger reboot was my only recourse...) when LW was or had been launched.
Any idea what I could do?