One thing I have noticed since upgrading to Windows 10 is if you use any program like MSI AfterBurner or EVGA Precission X the OSD for the RiviaTuner/Server will mess with UE4 4.9+ you either need to uinstall them or turn them off and shut down the RiviaTuner Server if it’s up which it normally has it’s own icon that looks like a monitor with purple number in the corner. Apparently how Windows 10 handle graphic hooks conflicts with On Screen Display and UE4 mainly for those programs. I have an i7 950 3.06Ghz (3.3 Boost), 24GB DDR3 G.Skill RAM and a Titan X 12GB so ya even with that machine just having AfterBurner/Precission X/RiviaTuner on/running really kills performance. Hope it helps some.