[Zope] Performance Hit

Hi; I want to call parts of the "pages" Zope serves from a MySQL database. My programmer tells me there would be a performance hit. I have a hard time understanding why (or if there is, I think it would be small). After all, Zope itself calls everything from a database (ZODB) and all of this activity would be server-side. There will be nothing complicated in the call: four simultaneous calls per page served. Is this problematic? TIA, beno