For what it's worth, I keep task manager open, but minimized all the time. It displays an bar graph representation of CPU useage in what I've always called the system tray for years, but apparently it's proper name is the notification area. Anyway it's in the lower right hand corner of the screen.
If the graph is maxed out you will see a slowdown in typing characters appearing. I usually have a couple of web sites open that do frequent live updates and I will see CPU useage go to 100% briefly during those updates. When that happens I just wait a few seconds and then everything returns to normal.
