Xperia X Performance owners have had to suffer with issue with their phones' accelerometers for a while now. The bug, when triggered, makes the phone's accelerometer quit responding entirely, resulting in inconveniences such as not being able to rotate the phone's display. Users had been going back and forth with Sony support on the official forums for weeks, as well as exchanging various workarounds like disabling Google location history. Ultimately, the fix for most people boiled down to having to reboot their phone each time it happened, which was reportedly 8 to 10 times per day for some users. After multiple users sent in device logs to Sony when the issues were happening, it seems that the Japanese OEM has finally managed to reproduce the issue and create a fix that is working for users.
The patch will bring users' build numbers up to 35.0.A.1.297, and is currently rolling out to all variants of the Sony Xperia X Performance. The patch doesn't include much in the way of under the hood extras or new features, but is supposed to fix the issues that Sony has been getting reports of, mainly the aforementioned issues with the accelerometer. Users who have already gotten the patch are reporting that the issue is fixed, along with other issues that had been reported and were possibly related, like similar problems with the barometer. Some users who have not yet gotten the patch are also reporting that the issues are fixed in the latest version of the Xperia Beta, which is based on Android 7.0 Nougat.
As of now, no system dump has been put out on the web, meaning that users who may otherwise have no problem flashing manually are stuck waiting for the OTA update to drop. The patch is still rolling out globally in stages for both the single and dual sim variants of the Xperia X performance, so if you aren't on the Nougat beta and haven't seen the update drop by just yet, you may have a bit longer to wait, though as with waiting for any other update, a reboot can't hurt. Sony has not made it clear whether those on the Nougat beta will get the update, so if you're on the beta and having the issue, going back to stock firmware may be your only way to get the update.