Dog slow as compared to what?
As compared to commodity server-class Linux/Intel hardware (which will cost you around 1/4 to 1/3 what the "equivalent" Solaris rig does).
I would prefer to do the absolute minimum in terms of tuning. Most of my experience with Zope and otherwise is with Windows. Can I potentially get by just installing and running? How would it run that way on a current Solaris server with appropriate memory compared to say running on a P4 3meg Win2003 machine with appropriate memory.
Let's put it this way: even if you get paid in cheese sandwiches, it will be cheaper to buy a 1U lintel box to run the server than the time you spend trying to figure out why it is so slow on Solaris, let alone the time you spend trying to remediate it. Unless somebody has a gun to your head, you should not run Zope on Solaris in *any* performance-critical environment.
FWIW, I offered once to *buy* the 1U for the client if it didn't smoke their big-iron Solaris box; they declined to take me up on it (but still went ahead and used Solaris, because that was what made the SAs feel warm-n-fuzzy).
Matt Hamilton's report is still probably your best resource if you find yourself with the gun to your head:
OK -- I get the picture I think ;-) I will try to dodge the Solaris bullet if I can.