Slow startup and UI lag on Windows XP while testing Oxygen

[teenagerimplement]

Hi everyone,
I’m currently testing Oxygen (latest version) and I really like the Tree Editor — it’s exactly the kind of structured XML view I’ve been missing. I’m considering buying a license to replace my old MS XML Notepad setup.
However, I’m running into a performance issue. On my machine, Oxygen takes a long time to start, and most dialog boxes feel very sluggish. Even simple actions in the Tree Editor (expanding nodes, selecting elements, etc.) have a noticeable delay. This happens both in the main application and in the standalone Tree Editor.
My system is Windows XP Home (no service pack), Compaq Presario, running JRE 1.4.0_01. I’m planning to update the JRE to a newer version to see if that helps, but before I do that, I wanted to ask:
Has anyone else experienced slow performance with Oxygen on older Windows XP systems?
Is this likely to be a Java issue, or should I look elsewhere?
Thanks in advance for any suggestions!