Just got a Razer Blade 15" laptop… and the editor runs great and my game runs great.
But the epic launcher uses like 75%+ CPU and causes the fans to kick in.
So weird - only the launcher does this - ue editor runs great and games run great.
If i kill launcher - cpu drops and fans turn off.
On my desktop - Epic Launcher doesnt use crazy high CPU … acts normal.
Any ideas?
So weird…
Easiest trick:
Run the launcher so that everything is up to date
Make a shortcut to the unreal editor (so you can launch any project)
Close out of the launcher
Navigate to it’s folder location and just add a 1 to the start of the launcher’s name.
DO NOT relaunch the launcher while it’s renamed or it will remember that exe name and continue to open in the future.
Any time you need to update something, take the 1 out of it’s name and open it.
This is will keep it from ever reopening on you when you launch the editor.
This is nasty workaround 
I use to create direct shortcut to the project and I’m all good.
“C:\Program Files\Epic Games\UE_4.19\Engine\Binaries\Win64\UE4Editor.exe” C:\Repo\MyGame\MyGame.uproject
Also I was using a trick with adding empty PerforceBuild.txt to Engine\Build folder, but I’m not sure if it’s still needed
https://answers.unrealengine.com/questions/17919/prevent-the-editor-from-launching-the-launcher.html
The editor will still launch the launcher after a few minutes. The perforce trick works as well though.
Thanks for the feedback… crazy something as simple as a launcher uses up that much cpu
A simpler solution is to go into the launcher settings and enable the system tray option. Once it is minimized to the tray, which can be done by closing the launcher, it will use 0% CPU/GPU.
Hope that helps! 
I found that rebooting my machine fixed it for me.
What kind of trash software from such a large company sucks away all your CPU and GPU power when the window is open and doing nothing? This company sucks a butt, and so does the management of BL3 for choosing such trash software.