amule is pretty resource-hungry on the Mac (probably mainly because of wxWidgets). Your primary limiting factor is probably RAM, because the 512MB you got is the minimum requirement for running Tiger.
However you should be able to tweak things a bit:
- Try 130 "Max Connections" instead of the 900 you are currently using.
- set your sources per file hard limit to 200 or 300 instead of 500
- What's the upload bandwidth your connection has? If it's only 16kB/s set your upload rate in amule to 10kB/s.
- In the amule preferences under Core Tweaks, set "Max new connections / 5 sec" to 7
- in Preferences->Source Dropping make sure you don't use "Send sources to other file before dropping"
- then there is some vodoo that Ken and I like to employ: when not interacting with amule switch to the Server List Dialog or the Search Dialog and then hide it using
.
Please report back your results. 