By default, CSS files in your <head> are render-blocking: the browser won't paint a single pixel until every stylesheet is downloaded and parsed. JavaScript files without async or defer attributes are also render-blocking — they halt HTML parsing entirely until the script downloads and executes. If you have three stylesheets and two synchronous scripts in your <head>, the visitor sees nothing until all five resources complete loading.
This is the #1 reason landing pages show a blank white screen for 2-3 seconds despite having decent server response times. The HTML arrives fast, but then the browser discovers it needs to fetch 300KB of CSS and 500KB of JavaScript before it can render anything. The visitor doesn't know that — they just see a blank page and consider hitting the back button.
How to fix render-blocking resources
For CSS: extract the critical CSS (styles needed for above-the-fold content) and inline it directly in the <head>. Load the rest asynchronously using <link rel="preload" as="style"> with an onload handler. For JavaScript: add defer to scripts that need DOM access, async to independent scripts, and move everything non-essential to the bottom of <body>.
The quickest diagnostic: open Chrome DevTools, go to the Coverage tab, reload your page, and look at how much of your CSS and JS is actually used during initial render. Most landing pages use less than 30% of the CSS they load upfront. That 70% is render-blocking dead weight.