Slow (spelled S-L-O-W) refresh sometimes

[hjellinek]

Describe the bug
I've noticed that Medley sometimes draws text very slowly, and other times acceptably quickly.

This is a screen recording of one of the slower examples, SEdit in this case. I see it in the exec sometimes too. But I just edited another s-expression of similar visual size in SEdit and had it flash onto the screen immediately. Why is it sometimes so slow?

To Reproduce
Steps to reproduce the behavior:

1. Set a variable FOO to the s-expression in the attached file.
2. In an Interlisp exec, evaluate ed(FOO)
3. Watch SEdit redisplay slowly, or maybe quickly! It's unpredictable, but once it's going slowly it stays slow.

Expected behavior
SEdit displays the s-expression quickly.

Context (please complete the following information):

• OS: macOS Ventura, SDL
• OS Version: 13.7.1
• Host arch: Intel
• Maiko version: commit 55d8504060d0d40505a2ddc39daca12f9ecb0303
• IL:MAKESYSDATE: 6-Nov-2024

Additional context
Add any other context about the problem here.

[nbriggs]

Which display subsystem? If X11, which Xserver?

[hjellinek]

Sorry, I threw it on the OS line: SDL.

I've been meaning to update the Issue template.