---
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"
published: 2025-11-03
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
---
<!-- docsgraph:related -->
## Related pages

> **For AI agents:** Follow these links to understand how this page connects to the rest of the Vercel ecosystem. For the full cross-link map (inbound, outbound, prerequisites, and semantic neighbors), see the .graph.md link below.

- [Insights](https://vercel.com/docs/observability/insights?from=related) — List of available data sources that you can view and monitor with Observability on Vercel.
- [Debug Slow Functions](https://vercel.com/docs/functions/debug-slow-functions?from=related) — Diagnose and fix slow Vercel Functions using CLI tools, logs, and timing analysis.
- [Functions](https://vercel.com/docs/functions?from=related) — Run server-side code on Vercel without managing a server.
- [Troubleshooting](https://vercel.com/docs/speed-insights/troubleshooting?from=related) — Learn about common issues and how to troubleshoot Vercel Speed Insights.
- [Legacy Usage & Pricing](https://vercel.com/docs/functions/usage-and-pricing/legacy-pricing?from=related) — Learn about legacy usage and pricing for Vercel Functions.
- [How do I lower my Vercel Function execution time?](https://vercel.com/kb/guide/how-do-i-lower-my-serverless-function-execution-time?from=related) — Learn how to lower your Serverless Function execution time.
- [Understand the Cost Impact of Function Invocations](https://vercel.com/kb/guide/understand-cost-impact-of-function-invocations?from=related) — Learn how to use Observability to understand function invocations and their cost impact.
- [How can I improve function cold start performance on Vercel?](https://vercel.com/kb/guide/improve-function-cold-start-performance-on-vercel?from=related) — Learn how to confirm whether cold starts cause function latency on Vercel, and how Fluid compute reduces how often they
- [Troubleshooting Inconsistent Logs in Vercel Functions](https://vercel.com/kb/guide/troubleshooting-inconsistent-logs-in-vercel-functions?from=related) — Learn how to troubleshoot and resolve logs that appear mixed in Vercel Functions. This guide explains why logs from diff

Full cross-link map for this page: [/kb/guide/investigate-latency-issues-and-slowness.graph.md](/kb/guide/investigate-latency-issues-and-slowness.graph.md)
<!-- /docsgraph:related -->


**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)