Hi @Miqi
Appears your experiencing a few issues with your phone !
Please ensure your phone's software is updated.
Try turning your NFC Off and On.
If that does not work then > Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
There is a diagnostic tool in your Samsung Members App.
A Samsung Service Centre can check out the phone.
I wish you all the best. 
