Moodle 5 slow performance despite good server resources

Dear Moodle Support Team,I hope you are well.We recently upgraded our platform fromMoodle 4.2 to Moodle 5, and since the upgrade we have experienced a clear and consistent performance slowdown across the entire site.Previously on Moodle 4.2, the system was fast and stable on the same infrastructure. The degradation started only after moving to Moodle 5.Affected areasDashboard(/my)Course pagesCourse category listingsLogin and session redirectsBoth guest and logged-in users are affected.Server environmentCPU:Multi-core dedicated server 8RAM:24 GBStorage:SSD 1.2Web stack:Nginx +Apache(Plesk)PHP:8.3 with OPcache enabledDatabase:MariaDBwith tuned InnoDB buffer poolCaching:Redis configured for Moodle sessions and application cachePHP OPcache activeCloudflare enabledServer resource usage (CPU, RAM, disk I/O) appears normal and not saturated.Observed behaviourSlower TTFB compared to Moodle 4.2Pages take longer to render even when cachedNo major plugin errors or PHP warnings visibleQuestionsAre there known performance changes or heavier background processes introduced in Moodle 5?Are there new recommended PHP, database, or Redis settings specific to Moodle 5?Are there core debugging or profiling tools recommended for identifying bottlenecks in Moodle 5?Is this behaviour expected under Moodle 5’s new architecture?We would appreciate guidance on optimizing Moodle 5 or identifying the root cause of this slowdown.Thank you for your assistance.Kind regards,Eamon