[Zope-CMF] CMF Default & Plone play well together?

[Jake]

Days later and I am still "deep diving" into Plone. I have installed it 
a few times and would like to throw together a first pass new site with 
it but am concerned about putting in a Plone installation in my main 
Zope/CMF site.

Does Plone as an installation over write anything in CMF Default? Can 
the two live side by side in the same Zope instance?

Also, just as a first pass, with the exact same content (meaning I put 
the Zope default welcome page as the Plone default page in a new Plone 
site) Plone seems to run about 50% slower than Zope alone. I need to 
try a default CMF install as well to compare.

Jake