your machine is slow as it needs to be cleared out and things turned off in the startup also depending on your antivirus you might be getting conflicts.
put it this way i'm still using an AMD 4300 and it does everything i need including 4k video via kodi. ok my graphics is a GTX 1050 Ti but its overkill for what i do.
my advice is to get a 8Tb USB external drive, dust out the internals of your old PC and get someone (not PC world) to give it a good old gut out data wise (i'm sure Gary will help you there)
you dont need a powerful computer for what you do and ignore the prompts for windozzzz11 its a marketing ploy.
i use
these desktop drives as they have the extra USB ports. i daisychain the drives but you can also use the ports for other devices like cameras and USB thumb drives etc.etc.