I’m currently on Windows 10, but this happened in Windows 8 as well. If I’m working in Atom, then switch to another program and then go back to Atom, there’s always at least a 10 second delay before any function works.
For example, I add some code in Atom, go to Chrome to check it, go back to Atom to modify the code. When I go back to Atom is when the delay happens. It does it every time, no matter what program I switch to or come back from.