I recently looked at MongoDB performance when it can't advance the majority commit point and it accumulates a lot of updates in the WT history store and oplog. (See WT-6776 and WT-6786.)  

We should test a related corner case.  In a PSA replica set where the secondary has failed and the history store grows a lot because MongoDB isn't advancing the stable timestamp, what happens if the primary then fails?  In particular, what is the effect on the recovery time for the primary.

As I understand, WT will run rollback-to-stable and need to get rid of most of that accumulated state in the history store.  So this is essentially asking how long RTS takes with a large (multi GB) HS file.