I have a difficult time trying to decide how to react to your post.
You ask support how to find out about memory spikes and they give you the answer, yet you don’t have time for anything like looking at logs. Do you think they should do this for you? Do you think they have more time than you do? Also you have only given us one tiny snapshot of what’s going on, and haven’t really told us import things, like “the spikes occur or don’t occur with any pattern like the same time everyday.”
Then you change subjects abruptly and want advice about page speed and page loading time. You say you have done all you can to speed up the sites, but don’t tell us what that includes.
Don’t be surprised if people are reluctant to help, while they may be able to offer suggestions you’ve said yourself that you don’t have time to deal with your site’s management. Unlike Staples there is no Easy button.