FB re-encodes everything to save bandwidth and you don't have much choice in the matter. That said, there may be potential to optimize your files, but without knowing what they are nobody can advise specifically.
It depends how big and the resolution image of your project. Facebook resizes all gif images to be 475px. So you can work around with this and maximum size is 8mb . Also for frame quantity count massively on the size, reduce the frame rate is a key process for upload gif on the internet.