Note: This is intended for more advanced users. If anyone wishes to write a comprehensive step-by-step howto, please let us know and we will post it as a sticky.

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The latest version of java allows you to really speed up the responsiveness of the Limewire GUI in a simple way:

1. upgrade to the latest Java (1.5.0 a.k.a. 5.0) from http://java.sun.com

2. make sure you have OpenGL-enabled X server. That means you should make sure the necessary server extentions are enabled. Also, if you are using an nVidia graphics card, you need to get the official driver from their website.
If you know (links to) good instructions how to do this for different graphics cards feel free to post them in this thread.

3. once you have done the first two steps, go to the directory where you installed Limewire and open the file runLime.sh with an editor. replace the line:

java -jar LimeWire.jar

with

java -Dsun.java2d.opengl=True -jar LimeWire.jar

The next time you start Limewire it will print out whether it successfully enabled the OpenGL pipeline. Once you know that everything works you can change the "True" to lowercase "true" and it will not print the message anymore. If java fails to initialize the pipeline, it will fall back to the default behavior - so you lose nothing by trying ;-)

Enjoy!

FWIW enabling this did not give me any noticeable ui speed increase. It did however cause limewire's ui to act very strangely, in that random areas of the ui (particulalry active swing components, like a menu) would have odd blocks of colored lines and minor distortions o fthis nature. Not that this has anything to do with limewire, just thought I'd let you know.
My specs are as follows:

limewire 4.2.5 on slackware 10.0, video card is nvidia TNT2 32mb

burn@nonteef:~$ java -version
java version "1.5.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-rc-b63)
Java HotSpot(TM) Client VM (build 1.5.0-rc-b63, mixed mode, sharing)

burn@nonteef:~$ X -version

Release Date: 18 December 2003
X Protocol Version 11, Revision 0, Release 6.7
Build Operating System: Linux 2.4.26 i686 [ELF]

burn@nonteef:~$ uname -a
Linux nonteef 2.4.26 #6 Mon Jun 14 19:07:27 PDT 2004 i686 unknown unknown GNU/Linux

--ps
forgot to mention that i am using the nvidia driver, tho it may be a bit out of date. I'm not sure how to check the version - in the meantime here is an excerpt from my xorg log:
(II) NVIDIA(0): NVIDIA GPU detected as: RIVA TNT2 Model 64/Model 64 Pro

thank you this worked very well for me

I too noticed that with the latest NVIDIA driver (build 6629) the difference is greater than before. Go Nvidia! ;-)