I have a problem with lag eating away at my work. I just realized this and I stopped using Google Docs. Those microseconds between keystrokes really make a difference in my writing productivity. It took me a while to figure that out. While typing, I'd expect the letters to keep up with me, but that often wasn't the case.
Now, I'll plow out my fast-typed prose in some other outlet before copying it over to Google Docs if I need it there for editing.
It's crazy. Some of these small, detail fixes that I've been doing have really been making a big difference.