I was having the same problem with 10.50 - 3fps before I even got off the ground. Removing KB3176938 brought my frame rates back to normal.
Thanks to everyone for the heads up on this problem!
69! Started out with Solo Flight from Mircoprose on the Atari 8bit and then flight simulator 4 on the IBM Compatible along with Sublogics ATP program which was way ahead of it's time. Flown about everything in between.
Blue skies!