We used Salesforce Community Page Optimizer.
Looks like Salesforce Aura framework takes the most of time of page load
window.Aura || (window.Aura = {});
window.Aura.bootstrap || (window.Aura.bootstrap = {});
window.Aura.appBootstrap = {"error":{"exceptionEvent":true,"event":{"descriptor":"markup://aura:clientOutOfSync"}}};
;(function() {
window.Aura.bootstrap.execBootstrapJs = window.performance && window.performance.now ? window.performance.now() : Date.now();
window.Aura.appBootstrapStatus = "loaded";
window.Aura.afterBootstrapReady = window.Aura.afterBootstrapReady || [];
if (window.Aura.afterBootstrapReady.length) {
var queue = window.Aura.afterBootstrapReady;
window.Aura.afterBootstrapReady = [];
for (var i = 0; i < queue.length; i++) {
queue[i]();
}
}
}());
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