I followed the steps from comment 19 and aftr update to Fx89 there is no reduced performance. @Steve C, could you please retest this on Nightly 91 to see if the issue is fixed for you?
Bug 1714069 Comment 21 Edit History
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I followed the steps from comment 19 and after update to Fx89 there is no reduced performance. @Steve C, could you please retest this on Nightly 91 to see if the issue is fixed for you?