DevTools cause Firefox to consume high CPU and memory on Microsoft 365 websites

[X-Celcius]

Is this a bug report or a feature request?

• Bug Report
• Feature Request

Please provide the steps to reproduce the issue [Bug Report only]

When accessing any Microsoft sharepoint or office page, Firefox starts to use around 50% CPU and uses an increasing amount of memory, way beyond 10GB after a few minutes.
Disabling Angular DevTools resolves the issue.

Please provide the expected behavior vs the actual behavior you encountered [Bug Report only]

Expected behavior: No noticeable performance impact by Angular DevTools, especially on non-Angular websites
Actual behavior: Extreme resource usage on some websites when enabling Angular DevTools

Please provide a screenshot if possible [Bug Report only]

No response

Please provide the exception or error you saw [Bug Report only]

I have tried to get a memory dump or profiling session from Firefox but it is incredibly difficult given that Firefox itself starts to hang after a few seconds and the only way to get it to be responsive again is to close the tab, which will also free up all memory. 

However, I have noticed that the error started roughly 1 week ago, when I also received the latest DevTools update 1.0.16. 
This update mentions: "Adding support for inspecting Angular applications inside iframes"

When I leave the console open when loading sharepoint it reports hundreds of these messages (among other things): 
IFrame: origin https://autologon.microsoftazuread-sso.com is not in the allowed list.
or: 
IFrame: Integrated Windows Authentication failed with status code 401 (Unauthorized).

These messages do not appear once I disable the extension. 

Blind guess: 
I come to the conclusion that the IFrame-inspection causes some issue with the Microsoft SSO mechanism. I read somewhere that authorization inside IFrames requires special attention due to clickjacking attacks: https://datatracker.ietf.org/doc/html/rfc6819#section-4.4.1.9
Maybe the inspection is interfering with this?

Is this a browser-specific issue? If so, please specify the device, browser, and version. [Bug Report only]

Running Firefox 126.0 (64-Bit) on Windows 11

Description [Feature Request only]

No response

Proposed solution [Feature Request only]

No response

Alternatives considered [Feature Request only]

No response

[JeanMeche]

I'm not able to reproduce it (On any Office 365 apps I'm able to access with a corporate account).

I could be related to #49518