use 90% of CPU

==== Required information ====
- iRedMail version: 0.8.7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: 7.4
- Related log if you're reporting an issue:
====
Hello,
this processes use 90% of CPU very often: 

www-data  9125 76.1  0.5  40612 23344 ?        RN   05:10   0:27 perl /usr/share/doc/awstats/examples/maillogconvert.pl standard
www-data  9119 12.6  0.3  40512 15264 ?        RN   05:10   0:04 /usr/bin/perl /usr/lib/cgi-bin/awstats.pl -config=smtp -update

also this processes use CPU very hard:

amavis   25248  2.5  1.8 238128 75276 ?        S    05:36   0:05 /usr/sbin/amavisd-new (ch17-avail)

Have any documents about configure iRedMail for minimaze use CPU ?
Thank you