If your performance tab is missing and you are an admin user, check if the performance is in use:
Click Access Button
then click HR Admin.
Click Settings then Performance.
Tick the box of In use from the upper side of the page.
If one performance review is missing, from that page go to the relevant review and check the In use box to be ticked.
You can also figure this out by the green tick which means it is turned on, and if it's grey it means it's off.