My 3-yr old Dell 9560 XPS is very sluggish.

... despite having such a score(XTU 986 marks), the system is slow. Very often it takes 2s to switch tabs and 5 to 10s to load the tradingview screen. I open the same number of windows and tabs on my work desktop of much lower CPU/RAM/HDisk spec but I get much better responses. I have just reinstalled Windows 10 Pro, but the system is still sluggish as before. System RAM utilizes 11-12 GB. System Info - Installed Memory : 32G RAM SSD : NVMe PLEXTOR PX-1TM9P

Any throttling occurred during the run? XTU is a nice stability tester but can in some cases provide a higher output than expected. Usually this happens if high temperatures occur (+75 C)