This guide shows you how to detect network issues or optimization opportunities in the Network panel of Chrome DevTools.
See Get Started to learn the basics of the Network panel.
Queued or stalled requests
Symptoms
Six requests are downloading simultaneously. After that, a series of requests are queued or stalled. Once one of the first six requests finishes, one of the requests in the queue starts.

logo-1024px.png
start
simultaneously. The subsequent requests are stalled until one of the
original six finishes.Causes
Too many requests are being made on a single domain. On HTTP/1.0 or HTTP/1.1 connections, Chrome allows a maximum of six simultaneous TCP connections per host.
Fixes
- Implement domain sharding if you must use HTTP/1.0 or HTTP/1.1.
- Use HTTP/2. Don't use domain sharding with HTTP/2.
- Remove or defer unnecessary requests so that critical requests can download earlier.
Slow Time To First Byte (TTFB)
Symptoms
A request spends a long time waiting to receive the first byte from the server.

wait
request was waiting a long time.
Causes
- The connection between the client and server is slow.
- The server is slow to respond. Host the server locally to determine if it's the connection or server that is slow. If you still get a slow TTFB when service locally, then the server is slow.
Fixes
- If the connection is slow, consider hosting your content on a CDN or changing hosting providers.
- If the server is slow, consider optimizing database queries, implementing a cache, or modifying your server configuration.
Slow content download
Symptoms
A request takes a long time to download.

elements-panel.png
means it took a long time
to download.
Causes
- The connection between the client and server is slow.
- A lot of content is being downloaded.
Fixes
- Consider hosting your content on a CDN or changing hosting providers.
- Send fewer bytes by optimizing your requests.
Contribute knowledge
Got a network issue that should be added to this guide?
- Send a tweet to @ChromeDevTools.
- Start a mailing list thread by emailing
google-chrome-developer-tools@googlegroups.com
. - Open an issue on the docs repo.