Glimpse shows execution timings, server configuration, request data and more, all in browser, with no changes to your application code. Just install the NuGet package, and you're good to go!
On one of our SharePoint Servers, we got a problem on activating a Sandboxed solution in a SiteCollection. The following error occurs: The sandboxed code execution request was refused because the Sandboxed Code Host Service was too busy to handle the request.