After toying for some time with slow startup on different Umbraco sites, it seems to be narrowed down to the initial rendering/compile of partials.

The result is that adding different empty partial views to an exisiting razor/cshtml template adds at least a full second to the initial load time pr. partial (adding the same partial multiple times only carries the toll once).

Im aware of the compile that goes on - but when comparing to a "normal" asp.net mvc solution where the overhead is a few milliseconds, the overhead with Umbraco installed is 1 second (and then some) pr. partial.

This has been tested on the latest version of Umbraco (7.10) aswell as a 7.4 and 7.3.8 (clean install using Nuget).

I found this thread - https://our.umbraco.org/forum/using-umbraco-and-getting-started/79800-why-may-partial-view-performance-be-so-slow which seems to pinpoint the same behavior but its un-resolved.

Do anyone have a workaround for this or is it download source and fix?

Steps to reproduce where the problem is pin-pointed and is narrowed down to "just" the load of partials.

Create a clean asp.net mvc app in Visual studio.

Compile and load up the default homepage.

Add 10+ partial views (empty) in visual studio

Include these in the _layout.cshtml code

 ....
 @Html.Partial("/Views/Partials/View - Copy (1).cshtml")
 @Html.Partial("/Views/Partials/View - Copy (2).cshtml")
 @Html.Partial("/Views/Partials/View - Copy (3).cshtml")
 @Html.Partial("/Views/Partials/View - Copy (4).cshtml")
 .... and more up to 20

Reload the homepage - this adds a few hundred milliseconds on the intial load.

Then install Umbraco from Nuget - walk through the installler - after this load up the homepage

After the initial load add the partials to the "master.cshtml" (equivalent to _layout.cshtml).

Reload the homepage - now this adds around a second pr. partial - ~20 secs with 17 partials in my case.