Machine very slow in v9.0

My machine is really slow since loading v9.0 I really can't find any reason for it. It can take 3-4 minutes to start a program for instance. There is nothing reported in messages as being unusual, vmstat doesn't show any mysterious paging, (my machine has 1GB Ram), top shows cpu idle as 98%, and I have no idea where to look next... Can anybody give me a clue? Phil