Since bug 1510280 landed, classifying many failures at once is very sluggish. The notifications are shown for a very long time, on production I also saw bug 1554007 during that action. Firefox's profiler shows there long DOM events and a Promise callback chain.
Bug 1555394 Comment 0 Edit History
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Since bug 1510280 landed, classifying many failures at once is very sluggish. The notifications are shown for a very long time, on production I also saw bug 1554007 during that action. Firefox's profiler shows there are long DOM events and a Promise callback chain.