By default the built-in Web Browser that is used on Windows to show web pages uses the Internet Explorer 7 rendering engine. Which means the Xojo HTMLViewer and the ActiveX WebBrowser controls also use this older rendering engine.
Healthcare.gov, the US Government’s health insurance exchange website for states that didn’t provide their own, was supposed to handle about 50,000 to 60,000 simultaneous users. Unless you have been living under a rock, you know what a complete disaster the website as been. But it didn’t (and doesn’t) have to be that way.