This won’t fix it but it might help.
Make sure you have a robots.txt file with a crawl delay set for all agents once every 30 seconds and that you are disallowing most of the WordPress directories such as WP admin, the media directory, etc.
I would also strongly recommend that you use a caching system if you are not using one. It’s a lot more efficient to serve the same image a hundred times to different bots from the ram than loading it off your drive.
Just my personal opinions working in a web hosting environment.
That’ll probably help if it’s i/o issues.
Whoever their host is, they already appear to have some type of load balancing based on the four IPS. But I would also agree that a free cloudflare account does wonders for most WordPress users. But that’s probably mostly because it filters out a shitload of bots and known bad actors. Just make sure you set up your origin certificates if you use a cloudflare account.