I don't think automatic reading of sites has anything to do with this
and I would recommend you turn it back on. It appears you are
referring to the automatic read when a site finishes loading feature,
which is a very good way to know when a site has loaded. Others may
know of a setting, but I doubt there is one. and changing settings
just to stop this unwanted automatic reading may have other
detrimental effects on other sites if something is available that may
stop this behavior.

I'll add that, as a comment on the situation, I have no patience with
someone who makes a tiny inconvenience into a major issue to the point
where it is a decisive factor in using NVDA or not. Using the stop
speech command is such a tiny inconvenience that I can't help but
wonder if the person simply doesn't want to change, no matter what. I
don't even consider it an inconvenience. Its so trivial that its just
something you do. I wouldn't be surprised if the person does trivial
things when using JAWS he/she might not need to do with NVDA.

Gene