I’m not actually advising the following option, but wanted to include it for completeness (and cheapness).
If you end up not going with the SSD, RAM or new computer option, or if you do and the SSD and RAM still can’t save it, you could back up any key data and do Chrome OS install to replace windows. Again, based on what you’ve said, this is probably NOT the best option for you, but I have found it to be viable on some of the old laptops I have lying around the house which were struggling to even browse the web. It is by no means a full featured OS by the standards of windows, but it is much more lightweight and good if all you’re going to be using an old machine for is web browsing and media playing.
But honestly, if the SSD and RAM doesn’t save the machine, it’s probably time for a replacement.