TCP packet size too small causing poor throughput

[shirhatti]

Originally reported by @mateanticevic

I have the same problem and noticed something strange. There's a huge amount of TCP packets as they are way below the MTU size limit. I reckon this is the cause of the slow download. This happens only with IIS in front of Kestrel. With Kestrel alone it doesn't happen.

AspNetCore MVC 1.1.1 ~675kB ~11500 packets ~2s download

Tested a similar call in an old app with Web forms and the difference is obvious.

Web forms ~675kB ~750 packets ~200ms download

[shirhatti]

@mcy94w Is it possible to capture packet sizes and number of packets in a one-off run as part of your ANCM perf tests?

[mateanticevic]

Thank you for opening this issue.
I noticed you've copied the wrong image for the Web forms example.

[shirhatti]

EDIT: Updated incorrect image

[shirhatti]

@mcy94w Do you think you'll be able to capture packet information?

[muratg]

We think in-process ANCM is not impacted, but we should verify.

[skashif]

I am facing a similar issue where the content-download time is degrading the performance. My issue is that when I access the sites on one of the VMs (irrespective of whether I am running it on the deployed server(VM) or not) I am getting the API response performance as below,

On another note, if I am accessing the website from my development machine which is not one of the VMs but a local desktop, I get the following response time,

Before I explain further, I would like to throw light on the application tech stack and versions -
API solution
.Net Core 2.1.4
Client
Angular 6
Host environment
Windows 2012 R2
IIS 8.5.*

So as you can see with hosting environment I have gone IIS + Krestel route but I have also tried hosting the API solution as a standalone using HTTPsys(formerly know as Weblistener) but the results were no different but even worse.

What am I trying to do?
My API returns a large JSON which has around 18K+ rows with Response compression (gzip) I have got down the response size to 1.9MB.

It would be great if someone could help me out here also,

1. Open to try a better approach to handle a large dataset?
2. Using different deployment techniques if that helps my cause?
3. Apply addition (IIS/Krestel) configs before deployment to make the API respond better?

This is a dealbreaker for me as you can notice I am making this data available in few ms so the response time is imperative for me.