Troubleshoot web page performance or page rendering issue in the Web Service
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Troubleshoot web page performance or page rendering issue in the Web Service


Article ID: 178908


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If you are experiencing web page latency or rendering issue when loading a particular site or mutiple sites via our Symantec Web Security.Cloud proxy servers, we will need to have the following questions answered, these questions and steps need to be taken while the issue is happening.

  1. Please visit and provide us with the output? e.g. text or screenshot.
    This will let us know what is proxy server your infrastructure is pointing to.

Performance (Latency):

One or more web pages are loading slow when going through the proxy.

  1. How long have you been experiencing the latency with the particular web page(s) via our web scanning service?
  2. Where does the latency occur? Is it at the initial lookup of the site hostname or is the entire site slow to load, e.g. images text etc.
  3. Is this happening to one particular site or multiple sites?
  4. Can you please provide us with some of web sites' URL that you are experiencing the latency with?
  5. How long does an example page ( for instance) take to load when going direct (no proxy) vs. proxy?


If the page is not rendering correctly, e.g. X within the image holders, missing cascading style sheets (CSS),

  1. Povide us with the web site's URL as well as screenshot of what is being displayed at the time of the issue.

For questions #6, #7, we will need to generate HAR files to provide us with additional information to help us diagnose the problem.

Generating HAR files

To compare the web page loading times when going direct (no proxy) vs. proxy as well as to gather more information about the web page not rendering correctly, please see the instructions below on how to capture HAR content depending on the web browser being used:

Internet Explorer:
The easiest way is using HttpWatch basic Edition (Free).

This tool is a GUI based tool which allows for viewing in real-time how long a page takes to load. The program lists all the sources that the page pulls all the content from and the time it takes to load each component in a page. It provides a holistic view of the page load time, rather than what is perceived by the user.

  • Download and Install HttpWatch.
  • Start the HttpWatch capture right before reproducing the issue.
  • Stop the HttpWatch capture right after reproducing the issue.
  • Export the capture to HAR format.

Starting with Firefox 41, HAR files can be created without any additional extension.

  • Start Firefox Developer Tools in Network mode by going to Top right menu > Developer > Network, or ctrl-shift-Q.
  •  Start to reproduce the issue.
  •  Once the issue has been reproduced, save the capture by right-clicking on the grid and choosing "Save all as HAR".
  •  Export the capture to a HAR file.

You can record your HTTP session using the Network tab in the Developer Tools in Chrome.

  • Open the Developer Tools from the Menu > Tools > developer tools), or by pressing Ctrl+Shift+C on your keyboard.
  • Click on the Network tab.
  • Look for a round button at the top left of the Network tab. Make sure it is red. If it is grey, click it once to start recording.
  • Check the box next to Preserve log.
  • You can use the clear button (a circle with a diagonal line through it) right before trying to reproduce the issue to remove unnecessary header information.
  • Save the capture by right-clicking on the grid and choosing "Save as HAR with Content".

.Please confirm with a selection of URLs the page-load times, direct/via the proxy, direct/via the client site proxy server or any applicable scenario for comparison below as well as providing us with the HAR file(s).

  Site URL No Proxy Browser>Proxy Browser>CSP Firewall>Proxy SC>ON LAN SC>OFF LAN

Once the requested information has been compiled and provided to the Symantec Technical Support team, we will attempt to recreate the issue on our side as some latency is expected when traffic is being routed through a proxy server.