Try running task monitor to see if anything is eating too much CPU or memory. Try different browser to see if that helps. Check free diskspace and free up enough space. Tried running anti-virus / anti-spyware utilities to see if something's up? Maybe it's time to reinstall OS? (backup important files first!)
Get Malwarebytes https://www.malwarebytes.com/ and Spybot https://www.safer-networking.org/dl/ Both free. Both excellent.
And both will find different things (you'll be surprised). Also Ccleaner. And remember that all these "cleaning software" things are only as good as their most recent update.
Doubt your computer is slow because it doesn't have enough horsepower... I'm running about the same as you and mine works like it should. Most likely you've got a software problem somewhere. Before you run out and buy a new computer, mount a different HDD/SSD and do a fresh install of Windows and your trading apps. Then install one other program (browser?) and see how things work. Then, another, etc. until you find the culprit. Any software can cause a system problem... browser, antivirus, utility... especially after an update that doesn't go just right.
Like many said get SSD or even NVMe M.2, multicore CPU cheapest one, integrated video, lot of fast DDR4 RAM like 16 GB at minimum. All this on latest windows and that's it. As for second monitor it's nice to have ability if you will use it. Do you use it ?