Poor Internet connection for downloading and working on C Xcode

I have a very fast internet at home in Japan but I do not trust it because the upload is 300MB and poor down load on OOkla and many speed tests so I am forced to go to town and get on the `free wifi ,but not safe better that infecting my Router and iMac newest OS computer at home.especially for technical work I want to develop Ainu Karelian language bi-lingual user OS like interface and many language Apps but there are many people who do not want this and target me and wreck my plans.so I work on paper.