Sketcher very slow, even on new sketch

[run_the_race]

If I try draw on a new sketch, it is painfully slow. There is nothing that depends on sketch yet, so I don't understand what is is recomputing. I marked the whole file as skip recompute, sketched a bit, then turned off skip recompute, and then got lots of errors. So I deleted that sketch and tried again.

I know about the Topological naming issue, and have already rebuild my models again to try make them as robust as possible. So now I am not sure what else I can do, I don't think my file is particularly huge.

In the free goto `Parts` -> `faceplate PART` -> faceplate BODY` -> then the last child called `SLOW SKETCH`, and try sketch on it. The time to draw a line is the same time to recompute the whole file, which for me is about 15-20seconds.

Is there something I am doing wrong? The warnings about `Links go out of the allowed scope` I was told can be safely ignored, and that they are a limitation of the Assembly4 workbench at the moment.

The file is here (at 1.8Mb was too big for a forum attachment):
https://www.mediafire.com/file/dhmo715n ... FCStd/file

Code: Select all

OS: Windows 10 Version 2004
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.6+
Qt version: 5.15.1
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/United Kingdom (en_GB)

[run_the_race]

Whenever I eventually give up and ask here I seem to figure it out... for any1 else who has this issue:
Unchecking `Auto update` under the `Solver messages` pane on left makes it not recompute the whole object.