Website very slow to load

HI there, I had an issue earlier on today, where the sites on this multisite weren't showing (nor the main site), this was resolved via support chat. Now I am finding that all the sites on this multisite are taking forever to load. It has taken over 10 minutes to login to the main dashboard. (I was going to check my Defender settings). Can you please investigate and see what is causing the issue please? The CPU keeps going up to 100% and back down again.