Normally, moving to a new user for troubleshooting doesn't require transferring all the normal account data.
Do a backup, preferable 2 separate ones on 2 drives. Boot to the Recovery Volume (command - R on a restart or hold down the option/alt key during a restart) and select Recovery Volume. Run Disk Utility and select First Aid. Reboot normally and test. It is possible your hard drive is beginning to fail. You might want to take it to an Apple Store fore testing.
If you live near an Apple Store, make a Genius Bar appointment to have the computer tested. Supposedly there is no charge for testing. Use 2nd link if not near an Apple Store or aren’t in the US. Hardware Repair - Keeping Confidential Data Safe
Take the original purchase receipt with you.
Genius Bar Reservation US
Authorized Service Provider