"If you touch the mysql.user table with a DML statement (i.e not GRANT/REVOKE) you also must do a FLUSH PRIVILEGES for these to be available for the mysqld process."
"@seattlegaucho Testing has shown that the creation without indexes does not improve performance. I don't recall the specific version, but the detection of an empty table and use of LOAD introduced a delayed creation of keys, as if you performed…"