The -nostartup do exactly what its name suggest: it run litestep without running the startup appz (HKLM/.../Run, HKKU/../Run,"Documents and settings/.../Programs/startup). It's usefull to restart litestep without restarting all appz that usually run at startup.
Use this to see if the slowdown is cause by litestep or an other app.
If the problem is solve while running litestep alone, then we can't do more for you: this is a litestep forum, isn't it ?
Humm, I suggest to uninstall every ICQ-like appz to make the test... I guess ICQ lite is a bit messy...