Exactly Phil this is the main thing to do and the other is to shut the chat in game off.
BUT
Clive this is when your F1 engine powered PC tries to run GPL in eco-sleep mode...
Please get the OpenHardwareMonitor.org activate the plot and check the load and clocks of CPU and GTX 1070 - those clock values have to be in full throttle as long as you drive. this graph shows their states.
Don't try to reduce any quality settings in NVidia driver settings this is contraproductive! You have to give the GPU some things to do to keep it awake.
So set everything in game to max (detail slider 99%) else your PC is yawning.