Driver booster 3.3 has a free version. It's slow on the download but it does install the drivers for you. I had a dogfight over the front in 1918 with regional air activity set to high and it ran 60fps the whole fight. Evidently windows 10 may use some generic drivers in the upgrade that don't offer the full hardware acceleration of the proper drivers. Once it goes out and gets the real Windows 10 drivers, there appears to be a nice boost for some people.