Optimizing cPanel resource usage

Hey everyone,

I'm hitting a wall with a persistent resource allocation challenge across several cPanel/WHM servers that we manage for our 'Website Maintenance & cPanel Management Services' clients. We provide comprehensive server management and, frankly, this specific issue is making it tough to guarantee consistent performance.

The core problem is intermittent but significant CPU and RAM usage spikes, primarily from httpd, mysqld, and occasionally lfd, especially during what should be moderate traffic peaks. These aren't sustained DDoS attacks or anything; it's more like a sudden surge that bottlenecks the entire server, leading to noticeable slowdowns for multiple client sites. Here's a typical htop snippet during one of these events:

# Example htop output snippet during a spike:
PID USER      PRI  NI  VIRT   RES   SHR S CPU% MEM%   TIME+  COMMAND
1234 nobody    20   0 1.2G  300M 200M R 85.0 15.0 0:15.12 /usr/local/apache/bin/httpd -k start -DSSL
5678 mysql     20   0 1.5G  500M 100M S 70.0 25.0 0:20.34 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/lib/mysql/hostname.err --pid-file=/var/lib/mysql/hostname.pid

We've already gone through the standard troubleshooting playbook: adjusting Apache MaxRequestWorkers, tuning MySQL innodb_buffer_pool_size and other buffers, optimizing PHP-FPM configurations, meticulously checking for rogue scripts or poorly optimized plugins in client accounts, and ensuring CSF/LFD are configured optimally without being overly aggressive. While these steps help mitigate the severity, they don't eliminate the underlying spikes.

I'm looking for more advanced server optimization techniques—something beyond the usual cPanel/WHM tweaks. Are there any specific kernel-level tuning suggestions, less common Apache/MySQL modules, or third-party solutions that have proven exceptionally effective for high-density cPanel environments? We need to stabilize resource usage consistently without over-provisioning hardware.

Help a brother out please...