Why is hidden _gsdata_ folder in the left and right sync folders so big?
Because _gsdata_\_saved_ folder keeps the last version of all files that GoodSync deletes or replaces, if option Job -> Options -> General Save Previous Versions of Files is checked. If you believe that you do not need these previous versions of files then: – Uncheck option Job -> Options -> General Save Previous Versions of Files. – Delete folders _saved_ inside folder _gsdata__ in left and right sync folders. – Do NOT delete folder _gsdata_ itself, GoodSync keeps state of synced files there.