RAM slow performance

Hello.

From the beginning of my VPS with Hestia, RAM never uses more than 2.5 GB of 4 GB. If I use memtester, my server use 100% RAM, but with backup users, for example, RAM is always behind from 2.5 GB and CPU is 100%.

It is possible than Hestia limit RAM usage?

Hestia doesnt limit the ram usage in any case :).