Glimpse should provide...a glimpse into what is causing the slow initial load without requiring you to write profiling code just to troubleshoot the issue. It is certainly worth checking out before doing the latter at least.
Also, StackExchange's MiniProfiler looks promising and may be worth checking out.
The fallback option of instrumenting your code to time its execution will be more work and require code changes of course; but if that proves to be your best option to understand the slow load times, so be it.