You Can Downgrade Your iPhone X
If you can't stand iOS 12.4.1's performance on your iPhone X you can try downgrading to the previous version.
Apple is currently signing iOS 12.4 which means you can use a loophole to drop your iPhone X back down in an effort to improve your device's performance.
Unfortunately Apple's closed off the downgrade path to iOS 12.3.1, iOS 12.3, iOS 12.2, iOS 12.1.4, iOS 12.1.3, iOS 12.1.2, iOS 12.1.1, iOS 12.1, iOS 12.0.1, iOS 12.0 and iOS 11 which means you can't move back to any of them.
If you're interested in how the downgrade process works, take a look at our downgrade guide.