In Firefox, displaying a list with many columns may cause the associated FirefoxCP Web Content process running at high % CPU usage.
Steps to Reproduce
1. Open Firefox 61.0.2 on macOS High Sierra.
2. Log in an instance containing several thousand task records.
3. Open Workspace/Lists/Incidents/All.
4. Save the list as for example All_Copy.
5. Open the All_Copy list.
6. Use Personalize Columns to add all columns to the list.
7. Open the Activity Monitor. Observe a high % CPU used by the associated FirefoxCP Web Content process. The CPU usage stays high even if there is no interaction with the UI.
After carefully considering the severity and frequency of the issue, and the cost and risk of attempting a fix, it has been decided to not address this issue in any current or near future releases. We do not make these decisions lightly, and we apologize for any inconvenience.
Related Problem: PRB1305938