Mozilla has introduced a number of new features to its pre-beta version of Firefox, including a system to make add-ons safer and a private browsing mode that blocks website elements designed to track a user’s online behavior.

“Our hypothesis is that when you open a Private Browsing window in Firefox you’re sending a signal that you want more control over your privacy than current private browsing experiences actually provide,” Mozilla said in a blog post. “The experimental Private Browsing enhancements ready for testing today actively block website elements that could be used to record user behavior across sites."

Mozilla pointed out that some websites may appear broken when their tracking behavior elements are blocked. To get around this problem, Firefox allows users to turn off the feature on a per-site basis. However, because Private Browsing mode doesn't keep any information about browsing sessions, when Tracking Protection is disabled for a specific site it only lasts for the current session.

The pre-beta version of the browser also introduces a new signing system for add-ons, making them a safer experience. The feature prevents Firefox add-ons from creating unwanted toolbars or buttons, collecting information, changing search settings or injecting ads or malware into devices.

Mozilla claims in the blog post that its Electrolysis project has meant a big performance increase for its browser. Electrolysis devotes a single background process to web content and further boosts speeds by utilizing all of a device’s computing cores. It is also said to increase Firefox’s security by sandboxing the web content process. Although the company warns that some Firefox add-ons may not currently be compatible with Electrolysis and might not work as expected or at all.

Mozilla says it is also working on bringing more new features to its Firefox browser, including an experience to help parents get added control of their children’s online browsing, more ways to connect with Firefox Hello Beta and a way to bring the full Firefox experience to iOS.