Be default, Umbraco 16+ disables runtime compilation for razor views in “Production” mode and instead wants you to precompile razor views at build time. We are wondering, is there a noticeable performance benefit to precompiling razor views? The downside to doing this means making hotfixes to razor views isn’t an option in production environments. Is this a standard best practice thing or is there a noticeable performance boost?
Here is the code in the Umbraco source code that now enforces the razor runtime compilation feature:
if (builder.Config.GetRuntimeMode() != RuntimeMode.Production)
{
mvcBuilder.AddRazorRuntimeCompilation();
}
Speaking only from my personal experience, yes, there’s quite a bit of impact on performance when not pre-compiling.
I usually notice it pretty quickly when a site has this disabled, as many pages will load exceptionally slow for the first hit and then pick up for consecutive requests.
Usually the impact is mostly felt after a deployment or recycle/restart but larger sites tend to be hit a fair bit harder then smaller ones.
If you have a well established CI/CD pipeline then pushing a hotfix to a view could be done pretty quickly.
Don’t get me wrong, I get that not having this functionality can be a bit of bummer, but it can also be blessing when someone forgets to push the hotfix to code and it later gets silently overwritten.
If you want, then you could do some benchmarking and post the results, might prove me wrong on my perceived “improvement”.
Regarding this:
Yes it is, and pre-compiling has, to my knowledge, been a way to improve performance of asp.net sites, since early days of .NET Framework.
At least I’ve worked on a fair amount of project on V7 that were using pre-compiling to greatly improve the performance of the platform.
It also enables compilation checks on build instead of runtime, making it potentially less error-prone.
I agree with Saeve that a good CI/CD would cause no issues with hotfixes. Just quickly changing a razor view on the server or just quickly manually uploading a razor file as a hotfix is a no-go in my opinion and should not be the reason for not precompiling razor views.
The first hits after a deploy are indeed the moments where you notice the biggest difference. After the first hit, the razor views are compiled, so the next hit is faster. But if you have a lot of views and a lot of visitors, you are taxing the server, and especially the cpu, a lot more when it needs to compile a lot af the same time. This can cause a slow site for some time after a reboot.