We are optimising a site and have read about the issue of the initial view lookup taking a long time. Subsequent lookups of the views are then much faster. Mini-profiler shows that a lot of the time is in the initial find view (I know I can use a ~ path to reduce this) and whatever else is done at this stage.
Where is the caching done? How long are view lookups etc cached? Can I see what is cached? Can we do anything to cause it to pre-load so there isn't a delay?
We have many views that are often not visited for hours and I don't want sudden peaks and troughs in performance.
We are using Azure and have a number of web role instances. Can I assume that each web role has its own cache of the view lookup? Can we centralise the caching so that it only occurs once per application?
Also I read MVC4 is faster at finding views? Does anyone have any figures?
The default cache is 15min and is stored in the HttpContext.Cache, this is all managed by the System.Web.Mvc.DefaultViewLocationCache class. Since this uses standard ASP.NET caching you could use a custom cache provider that gets its cache from WAZ AppFabric Cache or the new caching preview (there is one on NuGet: http://nuget.org/packages/Glav.CacheAdapter). Using a shared cache will make sure that only 1 instance needs to do the work of resolving the view. Or you could go and build your own cache provider.
Running your application in release mode, clearing unneeded view engines, writing the exact path instead of simply calling View, ... are all ways to speed up the view lookup process. Read more about it here:
You can pre-load the view locations by adding a key for each view to the cache. You should format it as follows (where this is the current VirtualPathProviderViewEngine):
string.Format((IFormatProvider) CultureInfo.InvariantCulture, ":ViewCacheEntry:{0}:{1}:{2}:{3}:{4}:", (object) this.GetType().AssemblyQualifiedName, (object) prefix, (object) name, (object) controllerName, (object) areaName);
I don't have any figures if MVC4 is faster, but it looks like the DefaultViewLocationCache code is the same as for MVC3.