Iphone X lagging on sound and vibration

Hello bougeotte,

Thanks for connecting with Apple Support Communities. We understand that you are having an issue with the sound on your iPhone X. To clarify, do you experience issues with the sound in multiple apps? If so, this may indicate that there is a hardware issue.

However, we suggest completing the following steps in order to further isolate the issue:

1. "Remove all screen protectors, films, or cases from your device. 
2. Check the speaker opening to see if it's blocked or dirty. On iPhone only, make sure that the receiver isn't blocked or dirty. 
3. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure that the brush is clean and dry.
4. Go to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need service.
5. If you hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can't hear, or hear static or crackling, then your network or reception could be the issue. Try to call again later, or from a different location"

More details here: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker

If the behavior continues, we suggest that you have your device evaluated by a certified Apple technician. You can follow this link for further direction: iPhone Repair & Service

Take care!