How to Completely Disable ‘Site Isolation’ via Group Policy in Microsoft Edge

Site Isolation is a fundamental security architecture in modern Chromium-based browsers, including Microsoft Edge. It forces each website’s rendering engine into a separate, dedicated operating system process. This process separation is the primary defence against advanced side-channel timing attacks (like Spectre and Meltdown) and cross-site scripting (XSS) vulnerabilities, as it prevents malicious JavaScript running in one tab from accessing the memory space (and thus passwords or session tokens) of another tab. However, enforcing a strict 1:1 process-to-origin mapping exponentially increases the browser’s RAM footprint and CPU overhead. In hyper-constrained virtual desktop infrastructure (VDI) environments, low-end legacy kiosks, or offline embedded systems where memory starvation causes critical system instability (and where external internet access is physically or topologically blocked), administrators may be forced to disable this security layer to maintain application availability.

This guide explains how to completely disable ‘Site Isolation’ via Group Policy in Microsoft Edge, explicitly opting out of Chromium’s strict multi-process security model in exchange for radically reduced memory consumption.

Disable Site Isolation via Group Policy

To enforce a strict configuration that prevents the browser from utilizing Site Isolation globally across all origins, we must deploy an administrative template. Note: This configuration should only be deployed in tightly controlled, isolated environments where the risk of arbitrary code execution via the internet is zero.

1. Log into Windows with an Administrator account.
2. Press the Windows Key + R to open the Run dialogue box.
3. Type gpedit.msc and press Enter to launch the Local Group Policy Editor.
4. In the left-hand navigation pane, strictly follow this exact path:

   Computer Configuration > Administrative Templates > Microsoft Edge

5. In the right-hand pane, locate the policy named SitePerProcess.
6. Double-click the policy to open its configuration window.
7. Select the radio button next to Disabled. (By explicitly disabling this policy, we instruct the Chromium blink engine to revert to legacy process management, grouping multiple origins into shared renderer processes to conserve RAM, thereby neutralizing the Site Isolation architecture).
8. Click Apply, then click OK.

Verify the Configuration Lockdown

Group Policy changes modifying the core Chromium rendering pipeline require the browser to read the registry upon its next launch and completely tear down its existing process tree.

Close all active instances of Microsoft Edge. To force the policy update immediately across the OS, open Command Prompt as Administrator and run gpupdate /force. To verify the restriction is active, launch Microsoft Edge and navigate to edge://process-internals. Look at the “Site Isolation Mode” header. It should explicitly state that Site Isolation is disabled globally. Furthermore, if you open multiple unrelated websites in different tabs and examine the Windows Task Manager, you will observe significantly fewer msedge.exe renderer processes running compared to the default state, confirming the drastic reduction in memory overhead at the direct expense of inter-process security.