---
title: "Comment by Rishabh Mishra on \"The API Wasn't Slow: Finding a 2-Minute Delay in the Delivery Path\" | Hashnode"
description: "The outside-vs-server replay is the cleanest part of this diagnosis. If the VPN is the suspect, I would run iperf3 across the tunnel during a load test and comp"
url: "https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff/comment/6af13773359e94320fd69f44"
---

[Discussion](https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff)

Comment [The API Wasn't Slow: Finding a 2-Minute Delay in the Delivery Path](https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff)

[Rishabh Mishra](https://hashnode.com/@rushdeploy)

[1d ago](https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff/comment/6af13773359e94320fd69f44)

The outside-vs-server replay is the cleanest part of this diagnosis. If the VPN is the suspect, I would run iperf3 across the tunnel during a load test and compare response size times requests per second with what the tunnel can actually carry. That usually separates a bandwidth limit from an MTU problem quickly.

[Akshita Gupta](https://hashnode.com/@codeincontext)

[21h ago](https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff/comment/6af13773359e94320fd69f44#reply-6af1f1f75bc4e54b52cb8138)

Thanks Rishabh. That’s the next step I’d take too. Comparing the data the test pushes per second with what the tunnel can actually carry should separate a bandwidth limit from an MTU problem. \[If you’ve done this before, I’d like to hear what numbers you usually see.\]

[Rishabh Mishra](https://hashnode.com/@rushdeploy)

[10h ago](https://hashnode.com/posts/the-api-wasn-t-slow-finding-a-2-minute-delay-in-the-delivery-path/6af0c4620ba174b457f411ff/comment/6af13773359e94320fd69f44#reply-6af287bc3f082ff44067a12d)

I don't use one fixed number, since it depends on the VPS and VPN type. I compare iperf3 throughput with the test's required throughput: if iperf3 is lower, it looks like bandwidth, and if iperf3 is high but large packets stall, I lower MTU toward 1400 and retest.