The artic.gr website is using a lot of server's memory

Hello,

The artic.gr website is using a lot of server's memory and my hosting provider suggest me to optimize the wordpress in order to solve the issue. The last hour we were under XMLRPC attacks, so the hosting provider block them through htaccess.

I am using in website your hummingbird plugin, and the total cache plugin also for optimization.

Do you have to suggest me any other way to avoid the high memory usage?

Any help will be appreciated.
Best Regards,
Kyriakos