Thread wait taking more time

Hi Experts,

We again have one Bt which is slow and when digged into the call graph we find that System.Threading.WaitHandle:InternalWaitOne is taking around 23 seconds. But after this we do not have any visibility after this. Looks like some thread is waiting for something which we need to investigate.

Name: System.Threading.WaitHandle:InternalWaitOne
Type: .NET Class / Method
Class: System.Threading.WaitHandle
Method: InternalWaitOne
Line Number: Unknown

How do we know what has to be optimised from the code perspective.

Any help is highly appreciated.