Look at the Cache-Control header and see if the site is telling the browser not to cache the JS. Also, look at the time-to-first-byte . . . if that is high, ma

Look at the Cache-Control header and see if the site is telling the browser not to cache the JS. Also, look at the time-to-first-byte . . . if that is high, maybe further tweaks to the cache plugin settings may help you. If you are not using at least PHP version 7.0 you will get a noticable improvement by getting to that as well.