Profiling Script with the Developer Tools

This content refers to an older version of F12 developer tools. Please visit our latest F12 tools documentation.

The Windows Internet Explorer 8 Developer Tools provide a built-in script profiler that enables you to profile the JavaScript code running in Windows Internet Explorer. This document outlines the high-level features of the script Profiler. For information about the F12 tools Profiler tab in Windows Internet Explorer 9 see Using the Profiler Tool to Analyze the Performance of your Code.

  • Introduction
  • Starting and Stopping Profiling
  • Viewing Profile Reports
  • Exporting Profile Data
  • Using Multiple Profile Sessions
  • Remarks
  • Related topics


Script profiling enables you to improve the performance of a website by identifying and fixing performance-related issues in JavaScript code. To open Developer Tools, press F12; alternatively, on the Tools menu bar of Internet Explorer, click the Developer Tools button.

Starting and Stopping Profiling

From the Profiler tab, start a script profiling session by clicking the Start Profiling button. This will put the script engines into profiling mode and change the text of the button to Stop Profiling. Perform the scenario you want to profile on your webpage. Click Stop Profiling end your session. The tool will automatically display the profile report just completed. The following screen shot shows the main user interface of the Profiler tab.Developer Tools Profiler

Viewing Profile Reports

The profile reports can be viewed with either the Functions or the Call Tree view, which can be selected from the Current View drop-down list.

  • The Functions view lists all the functions used.
  • The Call Tree view provides the hierarchy of calls.

In both views, various profile data is presented in different columns in the Primary Content Pane. To add or remove columns, right-click anywhere on the Primary Content Pane, and from the shortcut menu select Add / Remove Columns. To sort the report on a particular column, click the column header; alternatively, right-click any header and point to the Sort By submenu, and then click the column name. To rearrange columns, drag the column headers left or right.

Exporting Profile Data

To export the profile data of the current report to a comma delimited (CSV) file, click the Export Data button The Profiler's Export Data button., then in the Save As dialog box type the name of the file, then click Save.

Using Multiple Profile Sessions

To start a new profiling session, click the Start Profiling button again. To end the current profiling session and to display the profile report for the new session, click the Stop Profiling button. The profile reports for older sessions are available in the Reports drop-down list. To view the report of previous profiled sessions, select a profile report from the drop-down list.


To capture URL and line number information, you must enable script debugging in Internet Explorer. To do that, either Start Debugging from the Script tab or set this option from Internet Option: On the Tools menu, select Internet Options and then, in the Advanced tab, uncheck Disable script debugging (Internet Explorer).

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