JavaScript much faster with profiler enabled

By design Issue #935765


Oct 10, 2014
This issue is public.
Reported by 0 people

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Steps to reproduce


Repro Steps:


  1. Launch IE11.

  2. Go to

  3. Select a file that can be compressed (>25MB PDF will be fine).

  4. Open the developer console.

  5. Transmit the file to someone.

You’ll see in the console the time it takes to compress each chunk (it uses 25MB chunks). Now try the same operation, but make sure the profiler is running. You’ll see it will be much, much faster during compression.

Expected Results:


JavaScript processing will be as fast (or faster) without the profiler running.

Actual Results:


Dev Channel specific:






Should work with sympath: srv*;


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    Comments and activity

    • Microsoft Edge Team

      Changed Assigned To to “Rico M.”

      Changed Assigned To from “Rico M.” to “Curtis M.”

      Changed Assigned To from “Curtis M.” to “Louis L.”

      Changed Status to “Confirmed”

      Changed Assigned To from “Louis L.” to “Michael H.”

      Changed Steps to Reproduce

      Changed Assigned To from “Michael H.” to “Jianchun X.”

      Changed Assigned To from “Jianchun X.” to “Limin Z.”

      Changed Assigned To from “Limin Z.” to “IE F.”

      Changed Status from “Confirmed” to “By design”

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