Open Bug 1715624 Opened 2 years ago Updated 7 months ago

Copy and Paste Freeze UI on Wayland


(Core :: Widget: Gtk, defect, P3)

Firefox 89





(Reporter:, Unassigned)


(Blocks 1 open bug)



(1 file)

Using Firefox on Wayland the entire browser freezes for a couple of seconds when copying or pasting a large amount of data (such as an image).

Firefox should not lock up the UI in this scenario. Additionally a couple of seconds is extraordinarily long for 6MiB of image. (Although there may be some re-compression going on.

Ideally no tab would freeze, however definitely it shouldn't be the entire browser. Sometimes the system "this application is not responding" dialog pops up.

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Gtk' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Component: General → Widget: Gtk
Product: Firefox → Core
Blocks: wayland
Priority: -- → P3

Please attach your about:support.

Flags: needinfo?(kevincox)
Attached file about:support
Flags: needinfo?(kevincox)

Can you try latest nightly with async clipboard enabled (

Flags: needinfo?(kevincox)

I tested nightly with async clipboard and the browser no longer locks up on paste 🎉

It still takes a long time to paste (roughly the same as stable) but at least the browser doesn't lock up. So I think we can consider this done.

Flags: needinfo?(kevincox)

Can you please use firefox profiler ( to get performance data while long paste?

Flags: needinfo?(kevincox)

It looks like a lot of the time is spent in LZ4 which I guess is because the source image is a JPEG and Firefox always copies PNG to the clipboard.

Flags: needinfo?(kevincox)

I see. Yes, Firefox puts more than one image format to clipboard, I see:


I wonder if it's possible to disable such image conversions and just paste what we have.

You need to log in before you can comment on or make changes to this bug.