A majority of e-learning vendors would have built-in additional inclusive of their ability to conduct annual performance reviews. You could definitely modify the open source systems for providing you with some of the corporate essentialities. Some would be relatively cheap than others.
Creating a connection to e-learning vendors would be for instance, would not cost a lost. It would not be complicated programming. However, you would decide to add in an entire module such as performance evaluations would be time consuming and expensive. It would be expensive that you may very well be better off with an online learning vendor supplied system that has a built-in module made available for you.