What causes high-latency page loads after a build?

Question

As we trying to make more frequent builds (and as our site traffic has increased), we've noticed that during higher traffic, the initial post-build page loads spike to 20 or 30 seconds. Our builds are published by copying DLL's + PDB's to a single server which is sync'd to one other server. That file-copy generally takes a few seconds.

What are some contributing factors to this sort of initial latency spike? Are there any commonly taken steps to avoid this problem? (I can't imagine high-traffic site that perform multiple builds/day, if not multiple builds/hour, tolerate this sort of thing.)

Answer 1

The main cause of this delay is ASP.Net doing compilation on the pages during first load, transforming the aspx markup into code.

You can solve this (and is actually listed as the first advantage on this link) by doing a pre-compile during your build. Of course, the trade off to this is longer build times. More information is here: http://msdn.microsoft.com/en-us/library/bb398860(v=vs.100).aspx

If you're using MSBuild to handle your CI builds by using the AspNetCompiler task in MSBuild: http://msdn.microsoft.com/en-us/library/ms164291.aspx

Another advantage this has (And why I tend to use this even in development builds), is if you integrate this into your build process, and you end up with syntax errors on a page, the build will fail, instead of your users being the first one to catch it.

In response to your comment (my response was getting too long for a comment):

Actually, I wasn't even aware of the batch settings myself until now. It looks like setting batch to false makes sense during development to reduce initial load times there. But, it seems that doing so would make asp.net function in assembly-per-page mode, which can slow things down on larger apps. So, probably the best compromise would be in development environments, set batch to false to speed up development time, then use the web.config transforms to set it back to true for production, and use the pre-compiler during the production build. Then you'll only pay the pre-compilation costs once for both servers, and in a way that's not visible to users.