1963949 - Firefox Nightly GPU Dedicated Memory Leak with Prolonged Use and Private Browsing

Status: RESOLVED WORKSFORME

(Core :: Performance: Memory, defect)

Description

[E0]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:140.0) Gecko/20100101 Firefox/140.0

Steps to reproduce:

1. Open Firefox Nightly
2. Open a private browsing window in Firefox Nightly.
3. Use both instances for regular browsing activities (e.g., opening multiple tabs, streaming videos, or visiting media-heavy websites like YouTube).
4. Leave both instances running for an extended period
5. Monitor GPU dedicated memory usage using System Informer or Task Manager

Actual results:

• GPU dedicated memory usage by Firefox Nightly processes steadily increases over time.
• Memory usage continues to climb, eventually reaching close to the GPU's total capacity which in my case is 12 GB.

Expected results:

GPU dedicated memory usage should remain stable or decrease when tabs are closed or activity is reduced.

The GPU dedicated memory only decreases when Firefox Nightly is completely closed.

The issue occurs with a mostly default profile, with only minor modifications to about:config for smooth scrolling and enabling JPEG XL support.

Device Info

• Operating System:Windows 11 24H2 26100.3915
• GPU: NVIDIA RTX 3080 Ti
• GPU Driver: 576.28
• Firefox Nightly Ver: 140.0a1

Comment 1

[E0]

Attachment: Troubleshooting Information

Comment 2

[E0]

Hi Alice,

Sorry to bother you, and thank you for updating the categories for this ticket.

Could you please let me know if you've observed this issue on your machine as well?

Comment 3

[E0]

I disabled all extensions except Dark Reader to test if the issue is related to extensions.

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:jlink, could you have a look please?

For more information, please visit BugBot documentation.

Comment 5

[E0]

To further diagnose the GPU dedicated memory(VRAM) leak in Firefox Nightly, I created a fresh Firefox Nightly profile with no extensions or about:config changes. Even without opening a private browsing window, I observed that opening multiple YouTube tabs in a normal browser window causes GPU VRAM usage to increase steadily. However, closing the YouTube tabs does not reduce the VRAM usage. The GPU memory only decreases when I completely close the Firefox Nightly window

Comment 6

[E0]

It’s been a month since my last update, and the GPU dedicated memory leak in Firefox Nightly persists. As previously noted, VRAM usage increases when opening YouTube tabs (or during regular browsing) in a fresh profile with no extensions or about:config changes, and it only decreases when fully closing Firefox Nightly. I’ve tested this on the latest Nightly build(141.0a1 (2025-05-30)) and the issue remains unchanged.

Could someone please provide an update on the status of this bug or recommend further debugging steps? I’d be happy to provide additional details.

Thank you

Comment 7

[Justin Link]

Hi E0,

Thank you for your report! Would you mind getting a memory report (go to about:memory and click "Measure and Save") and upload that as an attachment to this bug so that we can get a better idea what we're looking at? 12Gb in the GPU process definitely sounds like a lot, and that report will tell us more about where it is going.

You mention in comment 5 that it is possible to reproduce this with a fresh profile and no extensions or about:config changes. If it is still possible to reproduce it like this, that would be the ideal scenario in which to obtain the report.

We really appreciate your taking the time to make a report and to follow up on it with us.

Comment 8

[E0]

Hi Justin,

Thank you for your response and for looking into this issue!

I’ve reproduced the GPU dedicated memory leak in Firefox Nightly using a fresh profile with no extensions or about:config changes.

Specifically, I opened a YouTube video, played it for a short time, then opened a new tab with the same YouTube video, played it briefly, and closed the previous tab. I repeated this process multiple times until the GPU VRAM usage reached approximately 6.1 GB.

The VRAM did not decrease after closing the tabs and only dropped when I fully closed Firefox Nightly.
I then measured and saved a memory report from about:memory

Comment 9

[E0]

Attachment: memory-report.json.gz

Comment 10

[E0]

Attachment: memory-report.json

Comment 11

[Justin Link]

Hi E0,

Thank you for the memory report. That report is showing pretty minimal memory usage (~43Mb) in the GPU process. In fact, the overall memory usage is low enough that it seems like the memory report came from a fresh start of Firefox, before anything much (like watching a video or navigating) had been performed. Re-reading your comment above, it seems like you captured this memory report after closing Firefox, is that correct? If so, can you repro it but capture it before closing it, while the memory usage is still very high? That would help point us in the direction of what's going on.

Comment 12

[E0]

(In reply to Justin Link from comment #11)

Hi E0,

Thank you for the memory report. That report is showing pretty minimal memory usage (~43Mb) in the GPU process. In fact, the overall memory usage is low enough that it seems like the memory report came from a fresh start of Firefox, before anything much (like watching a video or navigating) had been performed. Re-reading your comment above, it seems like you captured this memory report after closing Firefox, is that correct? If so, can you repro it but capture it before closing it, while the memory usage is still very high? That would help point us in the direction of what's going on.

Hi Justin,

Thank you for reviewing the memory report! I’m sorry for the confusion in my previous comment. I captured the memory report from about:memory (using "Measure and Save") before closing the fresh Firefox Nightly profile, when the GPU VRAM was at ~6.1 GB. To ensure a clean test, I’ll free the memory by clicking "GC," "CC," and "Minimize memory usage" in about:memory before reproducing the issue on a fresh Firefox Nightly profile. I’ll then attach a new memory report capturing the high VRAM usage.

Comment 13

[Justin Link]

Wow, if that was taken while you were still seeing ~6.1Gb of usage somewhere else, then we have a big discrepancy.

If you wouldn't mind, when capturing the next memory report could you try following these steps:

1. Use Firefox until you see high memory usage. Preferably with a new profile and as few extensions as possible.
2. Once you are in the high-memory-usage state, capture a memory report the usual way in about:memory.
3. Then, try the "minimize memory usage" button, maybe a few times.
4. Then capture a memory report again.

If possible, a mini-screenshot showing whatever other tool you're using to measure memory usage could be helpful as well. The best time to take that would be right around step 2 above.

This will give us some idea if we do have any discrepancy between what about:memory is showing and Task Manager/System Informer. It will also help us understand if the additional memory usage is usage that is just waiting to get released or more "permanent".

Comment 14

[E0]

(In reply to Justin Link from comment #13)

I followed your steps using a new Firefox Nightly profile with no extensions at all. I opened a YouTube video, played it briefly, opened a new tab with the same video, played it briefly, and closed the previous tab, repeating until the GPU VRAM reached a high usage state. In this state, I captured the first memory report from about:memory. Then, I clicked the "Minimize memory usage" button a few times and captured a second memory report.

During this process, the GPU VRAM readings in Task Manager and Process Explorer did not decrease at all, even after minimizing memory usage.

Notably, Task Manager showed a higher VRAM reading than Process Explorer, though both remained high and did not drop when closing tabs. The about:memory report showed a different reading compared to both tools.

I continued testing without closing the Firefox Nightly profile, pushing the VRAM usage to the limit (~12 GB in Task Manager). When approaching 12 GB, Firefox froze, and I found the following failure log in about:support:

(#0) Error	Killing GPU process due to IPC reply timeout
(#2) Error	CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#3) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#4) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#5) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#6) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#7) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#8) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#9) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#10) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#11) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#12) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#13) 	CP+[GFX1-]: CompositorBridgeChild receives IPC close with reason=AbnormalShutdown
(#14) 	CP+[GFX1-]: IPC Channel is already torn down unexpectedly
(#15) 	CP+[GFX1-]: IPC Channel is already torn down unexpectedly
(#16) 	CP+[GFX1-]: IPC Channel is already torn down unexpectedly

Interestingly, while approaching the 12 GB limit, Process Explorer’s VRAM reading dropped to around 1 GB before the freeze, while Task Manager’s reading remained high. After the freeze, Task Manager’s VRAM reading dropped to nearly zero. I also captured a third memory report after the freeze and failure log.

I’ve attached the first memory report (high usage state (memory-reportFirst.json)), the second memory report (after minimizing memory usage (memory-reportAfterMinimize.json)), and the third memory report (post-freeze (memory-reportAfterFreeze.json)), along with a screenshot showing Task Manager and Process Explorer VRAM readings.

Screenshot

During High Usage

During High Usage Task Manager
During High Usage Process Explorer
During High Usage about:memory

After Memory Minimize

After Memory Minimize Task Manager
After Memory Minimize Process Explorer
After Memory Minimize about:memory

After Freeze

After Freeze Task Manager
After Freeze Process Explorer

Comment 15

[E0]

Attachment: memory-reportFirst.json

Comment 16

[E0]

Attachment: memory-reportAfterMinimize.json

Comment 17

[E0]

Attachment: memory-reportAfterFreeze.json

Comment 18

[E0]

Attachment: Troubleshooting Information Raw data After Freeze

Comment 19

[E0]

Hi Justin,

It’s been 11 days since I uploaded the memory reports and screenshots. I wanted to follow up to see if there’s any update on the GPU dedicated memory leak issue in Firefox Nightly.

Please let me know if you need further details.

Thank you for your time and assistance.

Comment 20

[E0]

Duplicate of https://bugzilla.mozilla.org/show_bug.cgi?id=1847453 And https://bugzilla.mozilla.org/show_bug.cgi?id=1952340