On the Mac you can use Shift-T to bring up a dialog that lets you specify exactly what tempo you want. Type in the number and then hit enter.
You can also use the mouse to right click on the tempo slider to bring up a quick drop down menu that lets you choose from a range of values.
If you are toggling back and forth between between 1.0x and some other tempo, you can double click on the slider to toggle between the most recently set value and 1.0x. This also works on iOS by double tapping the slider.