Since I upgrade to 11.04, the new Ubuntu One daemon (syndaemon) is using 100% at somewhat random intervals. I'm not updating any files in the folder to my knowledge, so it's a bit confusing as to why it would do this.
Is this normal behaviour? If it is, then I understand, (only, when it uses so much CPU, my system becomes almost unusable!) :)
EDIT: OOPS! It wasn't actually Ubuntu-one (I had problems with it in the past and got the process name mixed up in my head/memory). Chipaca's answer is accurate for me.