There is a slight increase in CPU usage going from 6 to 22.08. This increase is small and attributable to the added feature set.
The original posted maxscale.cnf uses RCR while the ensuing discussion uses RWS.
If the problem does not abate, please re-open this Jira and provide the exact maxscale configuration, description of the load the applications generate, statistics using "maxctrl show maxscale" , "maxctrl show services" and "maxctrl show servers". Also during high load, "maxctrl show sessions" would be helpful.