I'd recommend a minimum of 8GB RAM, but if you can get 16, you should.

In my experience with JAWS it comes down to 2 things, RAM and CPU. The more RAM the better, but most come with at least 8 gig these days which is enough. If you do anything else heavy (excel maybe) you'll want more. As for the CPU, as long as it's an i5/i7 my wife hasn't had any issues. I think JAWS likes multi-core/hyper-threaded CPU's, so as long as it's not a mobile cpu (ARM) or a celeron, you shouldn't have any issues regardless of how fast it is.

I would go with at least 16 gigabytes of ram. JAWS is just as a large program as Zoom Text. Freedom Scientific has a demo version of JAWS that you can use, but you will have to restart your computer every 40 minutes in order to use JAWS. NVDA is also a great option. It is free. I personally prefer JAWS, but NVDA is a great substitute. I hope that this helps.

I've used NVDA on Windows 10 successfully and without any latency on a 1.6GHz passively cooled dual core Celeron CPU and 4GB of RAM. Screen-reading software, at least NVDA, is not that heavy.