scrub log cause high system load

The server is a brand new, dedicated mysql box, and here are the relevant variables in my.cnf

innodb_encryption_threads = 8
innodb_background_scrub_data_check_interval = 3600
innodb_background_scrub_data_compressed = 1
innodb_background_scrub_data_interval = 86400
innodb_background_scrub_data_uncompressed = 1
innodb_immediate_scrub_data_uncompressed = 1
innodb_scrub_log = 1
innodb_scrub_log_speed = 50000

After the service restarted, the total CPU usage is 0, and after a short while(several minutes, an hour, not quite sure), the total CPU usage grows to 15, and system load is up to 8. And after I comment the above variables, the system is back to normal.

Is there anything wrong with my configuration?

perf top -p ${pid}
Samples: 1M of event 'cycles:ppp', Event count (approx.): 278084696592
Overhead Shared Object Symbol
30.93% mysqld [.] fil_crypt_thread
29.82% mysqld [.] ut_delay
16.56% [kernel] [k] _raw_spin_lock
1.41% mysqld [.] PolicyMutex<TTASEventMutex<GenericPolicy> >::enter