ASP.NET MVC Performance Problem "Waiting for synchronization"

Question

I'm using ANTS Performance Profiler to investigate a performance problem in an ASP.NET MVC app.

The app asynchronously makes requests to controllers for different independent chunks of data using AngularJS services. When I use System.Diagnostics.Stopwatch to collect timing from inside the endpoints, they run quickly as expected. The app as a whole, however takes longer than the sum of those timings to load.

When I profile using ANTS Performance Profiler, I see that most of the time is spent "(Waiting for synchronization)"

Is ASP.NET doing some locking under the hood that I could tweak? Is this an erroneous reading from the performance profiler?

Answer 1

it looks like based on this answer https://forum.red-gate.com/discussion/20637/waiting-for-synchronization that "Waiting for synchronization" is the total time that all threads waited in aggregate. If you have ANTS set to "Wall-clock time" instead of "CPU Time," this number is large, but doesn't indicate a performance problem.