I have a client Magento 1.9 store running on our managed VPS service. Since a few days ago, admin area started to load very slowly. Even the login page takes 1-2 minutes to load. The store’s front-end pages load pretty fast
I have monitored server resources during admin page load and CPU usage does not go beyond 10% and memory usage does not go over 20%. Also, the server is running on pure NVMe disk and I/O wait percentage ofCPU (as shown in top command) is below 0.1%.
The server is running LiteSpeed web server and all php extensions and web server itself are up-to-date.
I have tried disabling Magento extensions one by one by moving their XML file to webroot/etc/app/modules/disable directory to see which extension is causing the problem. However, disabling none of them resulted in faster page load.
I have also tried cleaning all logs using shell/log.php script.
It looks like some part of code is blocking page load for a long time.
Any idea would be highly appreciated.