Accessing data from parent window is very slow

External Issue #14775345


Mark P.
Nov 21, 2017
This issue is public.
Found in
  • Microsoft Edge
  • Internet Explorer
Found in build #
Reported by 1 person

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Steps to reproduce

In my web app a child window accesses a state object on the parent window object. I found that repeated read operations on this object are very slow when compared to the same object being created on the child window directly.

I was able to create a simplified repro of the issue. Steps to repro:

  1. Extract the attached directory
  2. Browse to the Parent.htm file (I had to put the files on a local website so I could browse with “localhost” to avoid XSS errors)
  3. Click on the “Open Child” button to open the child window.
  4. In the child window, click the "Run Test on Parent Object". This traverses the data object that was created on the parent window. It will alert the time it takes to finish the traversal.
  5. Click on the “Run with Local Object” to run the same test on an object created on the child window. This test will run much faster.

I’ve found the “Run with Parent Object” test to be much slower in Edge and IE. On Chrome and Firefox there is no difference between running the loop on the child object vs the parent object.

I’ve worked around this by cloning the object to recreate it in the child window (serializing/deserializing works). I imagine I could have also used LocalStorage to transfer the data as well.


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Comments and activity

  • Microsoft Edge Team

    Changed Assigned To to “James M.”

    Changed Assigned To to “”

    Changed Assigned To from “” to “Milena S.”

    Changed Status to “Confirmed”

    Changed Status from “Confirmed” to “External”

  • This issue has been resolved External. This means this issue may require a new feature to be implemented or other work that is more significant than a typical bug. You may be able to find more information on this issue by searching for related features on and

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