You can check out Wax. It is very simple and free. There is also Blender and as far as I know, it is also free. But as a user of AE, I strongly suggest you to keep on using AE with simpler templates and more importantly, with simpler settings. If your pc performance is low, try using an older version of AE. Trust me, there isn't so much difference between older and newer versions if you are going to use it only for basic intros.