Ok I had confused myself a bunch because this thread is massive and things kept changing. Here is my summary of the current situation: The only problem being reported in this issue now is that webrender is too CPU intensive, especially with a heavy tree-style-tabs workflow. The user has ~1500 tabs, but most of those are "hibernated" on startup and never touched. However they likely accumulate non-hibernated tabs much more quickly than an average user, because that's the tree-style-tabs workflow! It is therefore possible that when webrender is enabled, we are doing more CPU intensive work that is somehow exacerbated by non-hibernated background tabs. Anecdotally I do think I saw this a few times while trying to see way more disastrous perf. With a 4 core (8 logical core) CPU, I remember seeing roughly the following in the OS CPU metrics (CTRL+SHIFT+DELETE): * 100% cpu while resizing the window * 50% cpu while changing/loading tabs * 20% cpu while scrolling bugzilla * 10% cpu idle These numbers aren't shocking, but perhaps they can be improved. Notably the user reports far better CPU usage with webrender disabled (didn't verify this myself). --------------- **Things That Previously Happened In This Thread That No Longer Matter:** In 68/69 beta the user was experiencing some sort of busy-loop deadlock. This went away ~3 weeks ago, which strongly suggests they were running into Bug 1566206, which was fixed and uplifted ~3 weeks ago.
Bug 1553074 Comment 46 Edit History
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Ok I had confused myself a bunch because this thread is massive and things kept changing. Here is my summary of the current situation: The only problem being reported in this issue now is that webrender is too CPU intensive, especially with a heavy tree-style-tabs workflow. The user has ~1500 tabs, but most of those are "hibernated" on startup and never touched. However they likely accumulate non-hibernated tabs much more quickly than an average user, because that's the tree-style-tabs workflow! It is therefore possible that when webrender is enabled, we are doing more CPU intensive work that is somehow exacerbated by non-hibernated background tabs. Anecdotally I do think I saw this a few times while trying to see way more disastrous perf. With a 8 core (16 logical core) CPU, I remember seeing roughly the following in the OS CPU metrics (CTRL+SHIFT+DELETE): * 100% cpu while resizing the window * 50% cpu while changing/loading tabs * 20% cpu while scrolling bugzilla * 10% cpu idle These numbers aren't shocking, but perhaps they can be improved. Notably the user reports far better CPU usage with webrender disabled (didn't verify this myself). --------------- **Things That Previously Happened In This Thread That No Longer Matter:** In 68/69 beta the user was experiencing some sort of busy-loop deadlock. This went away ~3 weeks ago, which strongly suggests they were running into Bug 1566206, which was fixed and uplifted ~3 weeks ago.