ASP.NET "End Render" slow under load even for empty page

Question

I have been having a performance issue that I can't figure out. Below is my page trace info which shows that all the time is being taken between "Begin Render" and "End Render". The crazy thing is this is for a blank aspx page! It also only seems to happen when server load is unusually high.

Any ideas what could be going on here?

aspx.page Begin PreInit

aspx.page End PreInit 0.000023 0.000023

aspx.page Begin Init 0.000037 0.000014

aspx.page End Init 0.000052 0.000015

aspx.page Begin InitComplete 0.000065 0.000012

aspx.page End InitComplete 0.000078 0.000013

aspx.page Begin PreLoad 0.000090 0.000013

aspx.page End PreLoad 0.000103 0.000012

aspx.page Begin Load 0.000119 0.000017

aspx.page End Load 0.000133 0.000014

aspx.page Begin LoadComplete 0.000145 0.000013

aspx.page End LoadComplete 0.000158 0.000013

aspx.page Begin PreRender 0.000171 0.000013

aspx.page End PreRender 0.000184 0.000013

aspx.page Begin PreRenderComplete 0.000199 0.000015

aspx.page End PreRenderComplete 0.000212 0.000013

aspx.page Begin SaveState 0.000290 0.000078

aspx.page End SaveState 0.000314 0.000024

aspx.page Begin SaveStateComplete 0.000328 0.000014

aspx.page End SaveStateComplete 0.000340 0.000013

aspx.page Begin Render 0.000352 0.000012

aspx.page End Render 5.987700 5.987347

Answer 1

Install a performance profiler (my recommendation from trying out many tools would be DotTrace (they have a free trial that is fully functional)) and profile your IIS application. There you will see exactly which method calls make up those 5 seconds.