---
title: Investigate latency issues and slowness on Vercel
description: Learn how to use Observability to investigate latency issues and slowness on Vercel.
url: /kb/guide/investigate-latency-issues-and-slowness
canonical_url: "https://vercel.com/kb/guide/investigate-latency-issues-and-slowness"
last_updated: 2025-11-11
authors: DX Team
related:
  - /docs/observability
  - /docs/observability/limits-and-pricing
install_vercel_plugin: npx plugins add vercel/vercel-plugin
---

**Problem**: One of your functions is timing out, not serving responses quickly enough, or otherwise alerting.

You can use [Observability](/docs/observability) to investigate and understand slow responses from your functions and its effects on function duration, error rates, and consumption. To do so:

1. From your [dashboard](/dashboard), select the project you want to investigate.
   
2. Navigate from your dashboard to the **Observability** tab.
   
3. Choose **External APIs** and set an appropriate time range filter (e.g. last 6 hours).
   
4. From the list, sort by **P75 duration** to find hosts with the slowest response times, e.g. `mycms.com`: {' '}
   
5. Select the hostname with high duration or error rate: {' '}
   
6. You can see a distribution of requests over time, as well as their latency. When selecting Functions, you can see which of your function routes sent the requests to the slow external API and navigate to the appropriate view right away.
   

## More resources

- [Observability overview](/docs/observability)
  
- [Observability limits and pricing](/docs/observability/limits-and-pricing)