Why does activating ASIO guard cause performance spikes?

Hello all.
Why does activating ASIO guard cause performance spikes? It lowers the performance but causes performance spikes at least in my case. Do I need to do something or accept, that it does not work on my system?

In theory, Cubase is looking ahead and precalculating audio but only when it has free time. So, it would be expected to increase cpu load but reduce drop outs

Then why do I get drop outs, when CPU load is 30%? Is it asio driver related?

Monitored tracks cant be precalculated. Are you using heavy plugins or VST instruments on a monitored track?
Something external to Cubase stealing cpu time?
And keep in mind 30% is an AVERAGE.

No monitored tracks no. Nothing external, I am 100% VSTi.

I have similar performance spikes as well when ASIO GUARD 2 is enabled.

By external, i mean something on the PC outside of Cubase like backup or antivirus?

I tried closing antivirus, but it does not have any effect. The guard still causes spikes from time to time. What about the other parameters below the asio guard box? Do they play a role?