Would you say THAT's slow? Or that it's "not very strong as a public facing website"?
(For what it's worth, I've used many content management systems, including Sharepoint. Sharepoint actually takes the cake for ease of use - Kentico confused the ever living daylights out of me, Umbraco just seems needlessly complex, DotNetNuke is an oversized abomination, and Sitefinity, well. $$$$).