1305634 - Bad performance during drag-and-drop operation

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect, P3)

Description

[antoine.gersant]

Attachment: profile.json

User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0
Build ID: 20160922113459

Steps to reproduce:

- Start Firefox 49.0.1 on Windows 10
- Access https://jsfiddle.net/5cvo0694/13/
- Using the Firefox Developer Tools, begin a Performance capture
- Hold the mouse to begin dragging the red square
- Vigorously wiggle the mouse (while still dragging the red square) over the list elements
- Keep wiggling for 5-10 seconds
- Release the red square anywhere on the page
- Stop the performance capture


Actual results:

The framerate during the drag and drop operation is inconsistent, and very low overall. See the performance capture attached. Note that this was captured on a high-end desktop computer.


Expected results:

The framerate should stay at 60, as it does in other browsers (verified in MS Edge 38.14393.0.0).

Comment 1

[Alice0775 White]

Could you paste the results of about:config (Help > Troubleshooting Information)?

Comment 2

[antoine.gersant]

Attachment: troubleshooting.txt

Added troubleshooting information. Let me know if there's anything else I can do to help.

Comment 3

[Caroline Cullen [:caroline]]

Retested this website and the drag performance and this is no longer an issue.