http://bugs.winehq.org/show_bug.cgi?id=18356
--- Comment #6 from Eduard - Gabriel Munteanu eduard.munteanu@linux360.ro 2009-08-27 18:43:51 --- It's not Wine's fault, Fallout 3 seems to do the exact same thing on Windows as far as users say. Bethesda broke quad core support with one of their patches. The fix is to add the option "iNumHWThreads=2" to your Fallout.ini (even if no such variable is defined there yet). You can add it in the "[General]" section.
I found it on the AppDB page; the first time I went through it the symptoms I was experiencing didn't look similar so I missed it. It's also described on other websites, unrelated to Wine and/or Linux.
I think this bug can be safely closed as WONTFIX. It's their fault after all and I don't how it could be fixed from within Wine.