Optimizing cPanel Server Management for High-Traffic SaaS Scalability

Hey everyone, I'm reaching out because we're at a critical juncture with our SaaS platform. We offer 'Website Maintenance & cPanel Management Services' and have been diligently running our operations on cPanel/WHM, but as we continue to grow, we're encountering persistent performance bottlenecks that are becoming increasingly difficult to manage. We've already implemented standard Apache and PHP-FPM tuning, exhaustively tweaked configurations, and optimized our database queries to the best of our current knowledge, but we're still consistently hitting limits, particularly during peak traffic periods. Our core technical problem manifests as significant CPU spikes and elevated I/O wait times across our multi-tenant cPanel servers under heavy load, especially when multiple concurrent users are engaged in database-intensive operations. The frustrating part is that while application-level profiling provides some insights, it doesn't fully pinpoint the root cause of these deep-seated server management issues. We've exhausted what we consider to be conventional optimization routes. So, I'm really looking for advanced strategies beyond just basic configuration tweaks. What are the most effective kernel-level optimizations that can be applied within a cPanel environment? Are there specific resource isolation techniques, perhaps leveraging CloudLinux configurations, that truly make a difference for high-traffic SaaS? We're also open to alternative web server/proxy setups – think LiteSpeed integration or Nginx as a reverse proxy – but need guidance on how to implement these effectively without breaking the cPanel ecosystem. How do you folks diagnose and mitigate these kinds of deep-seated server performance issues when the bottleneck isn't immediately obvious? Our ultimate aim is to achieve superior stability, significantly reduce latency, and ensure our infrastructure can scale seamlessly to support increasing demand for our services without requiring constant firefighting. Waiting for an expert reply.