This one is .NET (C# to be specific) and the other one was ASP
(VBScript). We're trying to consolidate our websites under the
same technology.
This one is supported by a company who we can call upon for guaranteed support, the other one does not have guaranteed support.
This one is supported in that it's being improved upon and new features
are being added, the other is for the most part becoming legacy
software with little to no continued development. This is
important due to new technologies in regards to servers, databases,
browsers, and expectations.
This one will scale whereas the other one doesn't. The
performance issues you're experiencing are more to do with the ads (our
poor little ad server) than this site.