My guess is that kAXWindowMovedNotification, kAXWindowResizedNotification, kAXMainWindowChangedNotification etc. are being listened to on the currently focused window using the Accessibility framework, and there is a callback which gets the latest position of the tracked window whenever it is fired, and uses that position as a reference to update the border position
The border window itself is most likely an NSWindow, which is why the tracking of the border with the target window feels quite sluggish
Edit: Found the source: https://www.eurogamer.net/maybe-ai-is-a-creative-solution-if...
λ omarchy master Ɇ » shellcheck -f checkstyle bin/* **/*.sh | grep error | wc -l
451
λ omarchy master Ɇ » cloc .
662 text files.
473 unique files.
253 files ignored.
github.com/AlDanial/cloc v 2.06 T=0.07 s (6645.0 files/s, 133055.1 lines/s)
--------------------------------------------------------------------------------
Language files blank comment code
--------------------------------------------------------------------------------
Bourne Again Shell 125 704 319 3344
Bourne Shell 237 499 229 1952
CSS 41 122 22 653
TOML 19 113 9 612
XML 3 6 12 437
Lua 12 0 0 151
INI 14 20 0 78
JSON 13 0 0 67
YAML 4 4 0 50
Text 2 0 0 36
JavaScript 1 1 0 20
Markdown 1 5 0 5
SVG 1 0 0 1
--------------------------------------------------------------------------------
SUM: 473 1474 591 7406
--------------------------------------------------------------------------------
[1]: https://lobste.rs/s/iuvukw/word_on_omarchy#c_slymk91. They co-opted the free software movement and made it more business friendly.
2. They convinced people that Open Source is pure and software that isn’t Open Source is unclean.
3. They convinced a bunch of developers that their definition of Open Source that was specifically crafted to protect business interests is canon.
4. They convinced a well meaning subset of those developers to police the other devs and pressure them to release their software under big tech approved licenses.
You're still sharing nvme IO, cpu, memory bandwidth, etc. Not having a VM isn't really the point. (EDIT: and could have been done with non-metal aws instances with direct-attached nvme anyway)