DT+ Preview= Memory overload!

Whenever I open a PDF I created in DT, it slows my system to a halt. I looked at what is happening in Activity Monitor, and from what I can tell, opening a 50mb PDF, results in Preview using over 1.5GB of RAM.

I don’t have anything else open with Preview, and have tried closing all other apps, opening other PDFs in DT, but it still happens. Adobe Reader opens the files just fine.

Dunno if it helps, but I am running the following:
Macbook pro 2.8ghz Intel C2D
4GB Ram
500gb HD (about 50% used)

I’ve run Techtool, Diskwarrior and fixed permissions, etc. Nothing’s helped. I did recently update DT, fwiw.

Thanks for any help.