Need urgent help to stop Onenote 2007 memory lag

[Turiba]

I use onenote a lot, but whenever I'm handwriting, it becomes really slow;
memory goes up to the sky (onenote takes +400 mb). I have to close it, and
open it again, happening every 20 or 30 minutes. It's horrible. But when I'm
typing, no problems, runs perfectly, and I love Onenote anyway.
My version is the RTM and I already re-installed it twice.
Any help?

Thanks.

Arthur