This seems to only happen on Facebook (Firefox), and I am not sure what is causing it. I am using a wireless keyboard that I left charging over night so it's not a weak battery. I have just reset windows 10 today because of a malfunction/malware that somehow got on my system... anyway it's an almost brand new system, the only thing needing to be replaced is the GPU. I'll be typing along and all of a sudden nothing shows up for a few seconds, then the letters appear.