Mainly load in a wp server would be mainly caused by php processes and mysql. So run and follow the mysqltuner recommendations to tuneup the mysql configurations and increase the configurations of php-fpm processes under,
pm = ondemand
tuning above parameters may help to avoid unwanted process swap and thereby cpu overhead caused by it.
Also we can increase the redis cache size (
maxmemory) in case if you are using redis and you have more cacheble contents.