TinyMCE exceeds maximum recursion depth

[ioweuiraosjfosj]

Writing a new blog post in WordPress, my browser becomes incredibly slow. I can hardly move the text cursor in the default TinyMCE editor. When I switch over to plain text mode, everything works fine. Also in WYSIWYG mode, the editor used to work fine a couple of updates ago. So the bug must have been introduced recently.

Then, the JavaScript logging caught my attention, since TinyMCE seems to exceed the maximum recursion depth when movind the cursor (see trace below).

My setup:
WordPress 4.3
Opera 12.16
No additional admin/editor plug-ins installed

[13.09.2015 21:16:00] JavaScript - http://www.example.org/blog/wp-admin/post-new.php
Event thread: keyup
Uncaught exception: RangeError: Maximum recursion depth exceeded
Error thrown at line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))
called from line 8, column 37634 in i(e, t) in http://www.example.org/blog/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4203-20150730:
    if(!i(e[n],t[n]))

[azaozz]

Duplicate of #33617. Fixed by updating to TinyMCE 4.2.5 in trunk and 4.3.1.