thanks for your feedback.

I found a bug in the music library part of Remote Buddy (used by both 
the AJAX Remote and built-in on-screen menu) that will reload the 
iTunes XML library with almost every item you access through Remote 
Buddy's interface, which - with a PowerBook G4 and a collection as 
huge as yours - can highly likely mean a very noticable performance 
hit. The bug is already fixed in my private build, though and even on 
my Intel machine and "only" about 40 GB of iTunes media, that gives me 
a noticable speed bump.

That still does not explain though, why the execution of a simple 
action like "next track", should be so slow. These actions do not 
involve the library objects at all and also don't need much bandwidth. 
So I guess that this may be a network issue.

In general, a good way to check whether it's a network performance 
problem (f.ex. due to packet collissions with other near-by WiFis 
using the same channel) is to access the AJAX Remote localy via Safari 
( http://localhost:8888/ ) on the Mac you run Remote Buddy on.

If you need help to diagnose and solve the most common WiFi problems, 
be sure not to miss the FAQ on the Remote Buddy site - especially the 
one on interrupting and breaking down WiFi connections.

Best regards, 
Felix Schwarz