What if you remove the code you added to defer parsing JS? Did the site speed back to 5-6 seconds from the 54seconds?
PS: The article you’re trying is 3years old, and the filter used in that clear_url is also deprecated. So try some new solution or try using any Cache plugin, that will help you to reduce loading time, instead tackling each issue separately.
I tried now and it says 6seconds, TwentySeventeen has low loading rates because it is not a multipurpose WordPress theme, my suggestion is to try some CDN ( optional 0 and also a good Cache plugin, that will resolve most of the issue you’re telling. Please try a cache plugin and wait for sometime to see the speed effects.