As a user pointed out, you can try this: Settings → Optimize battery usage → Click on "Apps not optimized " and select "All" → Search "com.samsung.android.biometrics.app.setting" → disable. It significantly improved speed and accuracy of my fingerpri...

Wow. This was revolutionary. Thanks bro. Significant improvement.it's still very laggy sometimes, but at least i don't want to bang my head on the wall every time i try to unlock my phone

I would have no issue with slow speed. But half the time it won't match.

No. I still have the thin plastic film that came on the new phone

Ive done that already. all my fingerprint saves are for one finger, yet it keeps failing to unlock phone.