While Sling has upgraded its interface a few times before-most recently with a slicker look on Apple TV devices-the latest changes are more fundamental. Hopefully that’ll change before Sling rolls it out to its regular subscribers. There’s just one problem: The pre-release version I’ve been testing can be excruciatingly slow, especially while using the channel guide. Now that I’ve had a chance to try the new Sling app myself, I can confirm that it’s a big improvement. The update, which is rolling out now on Amazon Fire TV devices and and heading to other platforms throughout the year, gives Sling a more modern look, simpler menus, and a some new navigation features. Sling’s interface has always felt a bit crusty, especially compared to slicker live TV services like YouTube TV and FuboTV. When Sling TV started teasing a new version of its app last week, it looked like a major step up for the live streaming service.