This was taken from here:
Start Open Office and click on Tools > Options. This should open the configuration. Click on Memory in the left menu and change the following settings:
Number of Steps: 30
Use for Open Office: 128
Memory per Object: 20
Number of Objects: 20
And how to disable java, which I don't recommend for the portableapps install.
I did it, and it works.
It seems to open faster(that could be cause I opened it twice in a row tho), and it scrolls large documents smoothly, even with graphics.