Open Office 3.1 is slow on my Jaunty 64 bit, but not on 32 bit

[The Eye In The Sky]

Dear all,

I am using two laptop, Fujitsu S6520, one with 4GB RAM (mine) and the 
other with 2GB RAM (wife's).
For the 4GB RAM, I am using Jaunty 64bit, where the 2GB one is using 
Jaunty 32 bit.

Then I install the Open Office 3.1 from :
deb-src http://ppa.launchpad.net/openoffice-pkgs/ppa/ubuntu jaunty main

The problem I have is that on the Jaunty 64 bit, the OpenOffice is not 
working smoothly. Every time I open a document in Writer which has many 
formatting, custom fields, pictures and tables (~30 pages, 700KB), the 
screen crawl.
Let's say I drag the slider to jump from page 1 to page 10, the page 
movement is not smooth, but jumpy and sometimes the whole screen will be 
darkened during transition (I think this is a feature from Gnome telling 
the system is unresponsive).
Or if I scroll my mousewheel, the movement of the screen is late so I 
ends up waiting the screen to scroll into the page I want, although I 
already release the mousewheel.

I thought before it was caused by the document itself, but when one day 
I borrow my wife's laptop update the document, I am surprised that on 
the 32 bit Jaunty, it has no problem.

Anybody have the same experience?

best regards,

Siva.