Has anybody found any scalability issues with ASP.NET web parts? I'm especially interested in finding a comparison between ASP.NET web parts versus SharePoint web parts for handling large numbers of concurrent users on the same web server.

I've been told that ASP.NET web parts can't scale as well as their SharePoint counterparts, but I haven't been able to find any real documentation to confirm or deny that.

Thanks for any assistance you may offer,

Ken