It is a moderately large (~12500 lines, 585kiB) text
file with UNIX line endings (\n).  Mixed in with the normal text are
protocol logs that have \r\n line endings.  I have confirmed that
replacement of those line endings will stop the bug from happening.  The
bug happens with all 25.x versions I have including master, the earliest
one I can still test is from February 27th this year.

To reproduce, set a mark (C-Space) somewhere in the file.  Then
extend/shrink the selection region by doing Shift-PgUp / Shift-PgDwn,
going back and forth several times.  Once you've crossed a portion of
the file that has the "foreign" line endings, as soon as you take your
finger off the Shift key Emacs becomes unresponsive (the cursor
vanishes).  Several seconds later it starts allocating memory in an
apparently exponential fashion until it has exhausted both physical and
swap, while maxing out one CPU core.  The process must be killed.

Trying the same recipe with Emacs 24.5 yields a short phase of
unresponsiveness with the cursor vanished, then it returns with an error
message "Timed out waiting for property-notify event".

I consider this a blocker for the upcoming 25.1 release.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptations for Waldorf Q V3.00R3 and Q+ V3.54R2:
http://Synth.Stromeko.net/Downloads.html#WaldorfSDada