Comment 44 for bug 1596377

I've been having this issue on my Dell Venue Pro 11 tablet and my Lenovo e540 laptop for the last few months. Finally got annoyed enough to search for info and found this thread.

Can confirm that running

sudo mv /etc/xdg/autostart/at-spi-dbus-bus.desktop /etc/xdg/autostart/at-spi-dbus-bus.disabled

fixed the issue on both of my devices.