Adding compressions can significantly reduce the size of the data transmitted.

It is worth noting that since compressions happens at run time it can add considerable processing overhead which can in turn cause negative performance.

        gzip on;
        gzip_disable "msie6";
        gzip_vary on;
        gzip_proxied any;
        gzip_comp_level 6;
        gzip_buffers 16 8k;
        gzip_http_version 1.1;
        gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;

Has your compression been configured correctly?

https://gtmetrix.com/