The high CPU usage you are experiencing is normal, PicoScope was designed for specific reasons to use as much of the available CPU resources as possible.
That's very bad programming in my opinion. No software should use up 100% CPU utilisation all the time. If timing is an issue, WinNT/2k/XP has priority modes specifically to run real-time applications.
I am experiencing this issue as well. Even the mouse pointer is jerky. As has been said, everything runs fine, but the machine becomes extremely hot (I'm using a fanless industrial PC which runs WinXP SP2 on a Celeron-M 600 processor with 256Mb RAM). Since we run PicoScope all day, I am concerned it will overheat the PC or shorten the lifespan unnecessarily.