I follow, always follow, Nick's advice so I have his recommended defrag installed.
After a recent reinstall I did the standard 2xSpace with a reboot in between. Then 2xComplete/Name with a reboot between. (I had installed the UTs. GEX, and FTX Australia)
There was a stutterless experience, and after clearing up the shimmers it was close to the best flying I have enjoyed.
So then I put on a commercial Airbus 1 & 2 and a 737 PIC, and decided to do a Name defrag.
First run less than 5% fragmentation, seemed good. Then second run 50.8%, and after two more only to 50.1. I note that the program stops at about 27% and goes no further.
I will take it up with the manufacturer, but I would be glad to know if anyone has experienced this, and has a cure or explanation.