I have the SG2428P(UN) 5.30, currently running FW  5.30.18 Build 20260310, standalone mode. First symptom I noticed on first boot was slow responsiveness - clicking any item on web management interface required several seconds to load the page. I have many tp-link switches in my network - some over 10 years old - and all of them react much faster than this brand new one. Another symptom is that CPU load indicated under Maintenance->CPU monitor constantly hovers around 45% on idle, and easily jumps to 90+% when I use the web management interface. The switch has default configuration - only updated to latest FW and set up administrator password, only one computer connected and browsing the UI. When delivered, the switch had a previous firmware version (I don't remember which one) - but upgrading didn't change anything.

Is it normal behaviour?