Slow multisites

Hello, we´ve been experiencing our sites to run slow both in the dashboard and a little bit faster on the front end. We´ve installed p3 profiler, hummingbird, wp super cashe and so on, but the sites are still extremly slow. Could it be the server or could it be the plugins?

It´s so slow that the awesome wpmudev defender plugin scans won´t even run.

When our site is ready we will switch to a vps server with 2xcpu 2gb ram. But now they are on a shared host.