Firefox on OpenBSD SPARC

I've been attempting to run OpenBSD on my Blade 100 since release 4.4.
 On 4.4 and 4.5, Firefox would always crash on certain JavaScript
heavy sites such as Google Docs.  I thought this was a bug and waited
for it to go away...

Now on 4.6 Firefox won't even start at all.  Just leaves a
firefox35-bin.core file.  This is on on a clean install - just ran
pkg_add kdebase and pkg_add firefox35 after the installer, nothing
else.

Now I'm starting to think this must be a configuration issue of some
kind?  I can't be the only one who uses Firefox on SPARC...