This is being actively addressed. You should already notice an improvement, but I believe we can do even better. I'm continuing to work closely with our hosting provider to fine-tune their server configuration. They've been excellent to work with -- the owner of the company personally responded to my support ticket and is collaborating with me on optimizing the setup.
Added later 8 d 2 h 37 min 45 s:
At my suggestion, I asked the hosting provider to
add all Cloudflare IPv4 and IPv6 ranges as trusted remote proxies in Imunify360,
remove any Cloudflare edge IPs that were incorrectly blocked in the firewall blacklist, and
enable Enhanced DOS protection and adjusted rate-limiting thresholds to prevent false positives during traffic spikes
You should notice a SIGNIFICANT increase in the speed of the site.
Added later 14 h 55 min 16 s:
Heh, might have spoke too soon. Grrr...