Sounds sort of like this issue (
https://lists.gnu.org/archive/html/help-gnu-emacs/2016-08/msg00010.html ) someone else reported on help-gnu-emacs.
@Alan Do the symptoms there match what you see?
FYI I haven't seen that issue happen for me.
Hello, Eli.
On Wed, Sep 07, 2016 at 09:04:55PM +0300, Eli Zaretskii wrote:
> > Date: Wed, 7 Sep 2016 17:39:25 +0000
> > Cc: address@hidden
> > From: Alan Mackenzie <address@hidden>
> > This suggests that Emacs gets "tired" after several hours, whatever that
> > might mean. Perhaps a buffer is getting depleted somehow, or something
> > like that.
> What buffer did you have in mind?
I don't have any particular buffer in mind. I simply don't know this
level of the software at all. (At least, not yet).
Maybe there's some circular buffer somewhere which, when it becomes
full, spuriously outputs a space to the screen. The buffer might well
not be in Emacs. Can a circular buffer gradually (over hours) become
smaller? That seems a bit unlikely.
I really haven't much idea - I've reported what I've observed, and I'm
speculating.