I don't have an HA unit to test but 50 minutes (or more) seems excessive.
I tested a configuration backup on a production FMC 1000 hardware appliance and it took 3 minutes 39 seconds. My lab FMCv took 5 minutes 9 seconds. (That's probably a best case for FMCv as it is managing only a single FTDv and is running on NVMe SSD.)