Recently there was a Gnome 3 update in Ubuntu which added some extra options. I noticed that whenever I would try to use my touchpad on my laptop, there would be a delay where it was completely unresponsive. To get rid of this, you can simply type in ‘mouse’ into the search box in Gnome 3 and click on the mouse icon. On the new window that opens up, click on the touchpad tab and uncheck the box under General ‘Disable touchpad while typing’. I’m not sure why someone chose to enable that by default as I found it very annoying.