High CPU usage by Apache/MySQL

Rate Per Second = RPS

Suggestions to consider for your my.cnf [mysqld] section

innodb_buffer_pool_size=22G  # from 128M to better accomodate your 262G of data
max_connections=256  # from 151 since you have had all connections used
thread_cache_size=150  # from 9 to reduce threads_created RPhr of 111
innodb_log_file_size=4G  # from 50M to support more than and hour before rotation
innodb_log_buffer_size=1G  # from 16M to support ~ 30 min before write to media

Performance should be significantly improved. There are many more opportunities to improve performance. View profile for contact info and free downloadable Utility Scripts to improve performance.