For scripts: if script is disabled for a document, scripts are not downloaded. See https://searchfox.org/mozilla-central/rev/a5d9abfda1e26b1207db9549549ab0bdd7

For scripts: if script is disabled for a document, scripts are not downloaded. See https://searchfox.org/mozilla-central/rev/a5d9abfda1e26b1207db9549549ab0bdd73f735d/dom/script/ScriptLoader.cpp#1620-1627 https://searchfox.org/mozilla-central/rev/a5d9abfda1e26b1207... as of today For stylesheets, I'm not certain how you're disabling them. Depending on how you do it, they may or may not get downloaded. The most common ways of disabling them result in them not being downloaded.