Please make sure that the JS link is valid(!) before adding in the text area: paste it in the browser’s address bar and try to load it. Do not guess.
Don’t worry about decreasing performance of your page by thinking that you are increasing the page load time – the plugin’s JS is ALREADY minified using Google’s Closure Compiler. In other words, there is no point letting W3 Total Cache to minify ALREADY minified JS file. When the latter happens, the Google map plugin stops working.