Windows 10 User here with the latest update, can't say that I have had any problems with lag on FZEP, runs fine with me.
I had a look through the most recent update notes and dont see anything that sticks out when it comes to causing problems with FZEP, then again, its not like they would say everything on the Windows update notes anyway.
I mean the first things I would probably ask is,
"What are the Specs of your Computer?"
and
"In Task Manager, does any of your Computer's Resources like CPU, Memory, etc, cap out at all while running FZEP or more specifically while it lags on FZEP?"
To be honest though, I'm not really sure why as I dont have the problem, however I replied to this more to say that I'm not experiencing the same problems.