Face properties fail to apply to parts of org-mode buffer

Question

Parts of certain file-visiting org-mode buffers fail to display properly. Specifically, the text is not displayed with the faces appropriate for this mode. The issue usually disappears when I invoke certain commands, such as org-cycle, but only for the visible portion of text exhibiting the issue; the issue will persist in other parts of the buffer. A couple of screenshots will probably better convey a sense of what I'm trying to describe:

The buffers that exhibit this issue tend to be large buffers, but I haven't been able to identify other patterns.

--

• GNU Emacs 28.1 (build 1, aarch64-apple-darwin21.5.0, Carbon Version 165 AppKit 2113.5) of 2022-06-01
• Org mode version 9.5.4 (9.5.4-gae168d @ ~/.emacs.d/straight/build/org/)

Answer 1

Bump the value of variable jit-lock-chunk-size with M-x customize-variable RET jit-lock-chunk-size.

jit-lock-chunk-size is a variable defined in jit-lock.el. Its value is 1500 Jit-lock fontifies chunks of at most this many characters at a time. This variable controls both display-time and stealth fontification. The optimum value is a little over the typical number of buffer characters which fit in a typical window.

Lately I am seeing folks using bigger monitors, hence bigger window sizes. I suspect the default value may be too low for such folks.

I am surprised that the value of the variable is statically fixed at 1500, even though the description implies that the value is based on one's hardware.

I am using a fairly low-end laptop, and the default value of 1500 is at one-third the value of 5000 or two-thirds of 2400 reported below.

*** Welcome to IELM ***  Type (describe-mode) or press h for help.
ELISP> (* (window-max-chars-per-line)  (window-body-height))
5032 (#o11650, #x13a8)
ELISP> 

One another reasonable value to start with would be

*** Welcome to IELM ***  Type (describe-mode) or press h for help.
ELISP> (* (window-body-height) fill-column)
2380 (#o4514, #x94c)

If setting the above variable is not satisfactory, scan the variables in M-x customize-group RET jit-lock RET or M-x customize-group RET font-lock RET for further points of experimentation or exploration.