Messenger’s split from the Facebook app added new features but quickly ate up device storage as the feature list grew. That’s changing — at least for iOS. On Monday, Facebook unveiled a completely redesigned Messenger app for iOS that only takes up a quarter of the space while loading twice as fast. The redesign, Facebook said, will be part of the plan to allow users to send messages to someone on different Facebook-owned messaging apps like WhatsApp or Instagram, as well as the plan to create a more privacy-focused platform.

The Facebook team focused on speed, size, and simplicity when redesigning Messenger from the ground up. The new design brings the app from more than 1.7 million lines of code down to 360,000, an 84% reduction in the amount of code powering the app. Less code means a smaller app, and the new app will take up less space — a plus for users constantly getting that storage space warning, as well as for older devices. Facebook says it took 100 engineers to rewrite the code.

Less code will also make updating the app easier, which could help bring new features to the app faster. Facebook says the redesign also makes the app simpler for users, since the previous version had oddities like 40 versions of the contact list.

The simpler, smaller app also translates to faster load times when launching. Facebook admits faster loading won’t be a big time-saver for everyone, but users who open the app several times a day will benefit the most.

The lighter version of the app doesn’t come without sacrifices, however. Facebook says some features are missing at launch but will be added to the app later. The company didn’t clarify which features won’t be in the initial launch, leaving users to guess as to which options will disappear when they update to the latest version.

So what’s to keep the app size from ballooning as Facebook adds those new features back in? Facebook has set size “budgets” for future updates, requiring new features to fall below a certain threshold in order to be added to later editions of the app.

Facebook originally announced the intention of completely redesigning the app at the F8 conference last year. The effort builds on Messenger 4, which is also designed to be simpler and faster, but by starting the app over from scratch, Facebook engineers were able to take those concepts even further.

“The work we’ve put into rebuilding Messenger will allow us to continue to innovate and scale our messaging experiences as we head into the future,” Facebook shared in a blog post. “In addition to building an app that’s sustainable for the next decade or more, this work has laid the foundation for cross-app messaging across our entire family of apps. It has also built the foundation we’ll need for a privacy-centered messaging experience.”

The Messenger overhaul will begin rolling out worldwide in the next few weeks for iOS devices only.