Here is my quickest way to reproduce that:
1. Open "level prototype 006"
2. Open any FSM there
3. Hold CTRL...
4. Start clicking and spawning new states as fast as possible...
5. ... vary fast it makes CPU peak for 2-5seconds each
^This is just one way to reproduce that. Because I have that same effect when trying to work very normally.
System specs?
Its PC, winxp, Intel Core 2 2GHz, 2GB RAM, Nvidia GeForce GTS 250