Firefox 52 shipped with e10s enabled by default for all users except those who are on Windows XP, have a windows machine with a touchscreen, or have extensions that are not compatible with e10s. It uses one browser UI process and one web content process.
Firefox 54 has e10s-multi, with multiple web content processes.
If you go to about:support in your Firefox 53, the "Multiprocess Windows" item in the first section ("Application Basics") should tell you why e10s is disabled for you, if it's disabled.