Possible reasons are:
- Modsecurity
- PHP sessions - High CPU Usage, 4CPU 8GB RAM - #19 by josephgodwinke
Recommended options for better performing litespeed server:
- MariaDB / MySQL Tweaks As Default & Option
- How to Find WordPress Performance Bottlenecks with New Relic on LiteSpeed/CyberPanel
- Disable and uninstall modsecurity use ImunifyAV/360 or Cloudflare or Crowdsec
- http://open.litespeedtech.com/mediawiki/index.php/Help:Modules:Cache