Following Jovo’s blog/question yesterday,
These scripts are necessary (obviously) to perform some of your site functions, but not all. However because they’re sitting in the header or above-fold, every time a user opens your site, they start to run, hence it slows down the loading speed. So the solutions can be to
(1) move those to the footer or
(2) let it run asynchronously (what the hell?) or
Those "clearing the cache" plugins seem to work a little. I've used W3 Total Cache, and followed the instruction by this guy exactly.
I have two websites using different themes.
(1) With GTmetrix, dramatically increased the score & "loading time" on both sites.
Now this site below tells you that, these scripts may be intentional by the developer, so if you do something (i.e. move to the footer etc), it may break the functionality. So "it's ok to leave the scripts there".
The same people say that you shouldn't care about Google Page Speed, the speed is what matters, not the score;
(Not affiliate links by the way - they sell premium cache-solution plugins)
But like Jovo says in his blog, those speed-checkers give different results and I don't feel I can rely on any of them. With GTmetrix, one of my sites was always slow (6 - 30 seconds depending on the time I test), but I changed the server location from Vancouver to London UK, it now always shows much faster rate (2-3 seconds)
Pingdom always gives me "super-fast" results, like 1.1 - 1.5 seconds.