OS: Win XP SP2 clean install
Limewire: 4.8.1
Internet connection: DSL

That's what the post Lord of the Rings linked to asks for. Other relevant information? As I've already previously posted, I feel it's an issue with the way the Limewire Windows theme works. However, since some of you feel otherwise:
RAM: 512MB PC2100 DDR
HDD: Toshiba 30GB 4200RPM
Display adapter: ATI Mobility 7500 32MB
Firewalls: XP SP2 firewall
Routers: Netgear MR314
JRE: 1.5.0 update 2

If you can tell me how that is relevant to my problem, I'd appreciate it. I'm not new to tech support (either side), and if you work with software enough, you learn enough to get a pretty good feel for what part of a program is causing problems. I don't mean this as an insult on any of your abilities; I *was* trying to help you out by narrowing down the list of possible things to look at---while it's certainly possible I could have prematurely eliminated a possible root of the problem, I was pretty careful.

Fabion: doesn't work. Besides, it was already at the default settings.

What would be nice is if someone else could please check out the theme I linked to. Apply it as your Windows XP theme and see if it causes Limewire to lag when you tell Limewire to emulate the Windows theme.