## Summary

On a HiDPI display, the screensaver saturates several CPU cores and drives the
machine into sustained thermal throttling. The cost scales with **device
pixels**, so it gets bad on a single 4K/5K panel and worse with more monitors.

Root cause is a combination of three things, all in the default configuration:

1. `omarchy-launch-screensaver` opens one fullscreen terminal **per monitor**.
2. `omarchy-screensaver` runs `ttfx` with a hardcoded `--frame-rate 120`.
3. Omarchy's only shipped/listed terminal is **foot**, which is a *software*
   renderer — it rasterizes with `libpixman` into a `wl_shm` buffer and links no
   `libGL`/`libEGL`/`libvulkan`.

Every screensaver frame is therefore rasterized on the CPU, full-screen, at
120fps, at native panel resolution.

## Measurements

Captured live while the screensaver was up (Framework 13, Core Ultra 7 165H,
Intel Arc iGPU, 3 monitors):

| Window | Monitor | Logical | Scale | Device px | CPU |
|---|---|---|---|---|---|
| foot | eDP-1 (laptop) | 1440x960 | 2 | 2880x1920 | 125% |
| foot | DP-4 (ASUS 1440p) | 2560x1440 | 1 | 2560x1440 | 103% |
| foot | DP-3 (ViewSonic 5K) | 2560x1440 | 2 | 5120x2880 | **303%** |

Total ≈ **531% CPU** (5.3 cores). Meanwhile `Hyprland` stayed at 9-11% and all
`ttfx` processes combined stayed under 10% — the compositor and the effect
generator are both cheap. The cost is entirely foot's CPU rasterization.

Thermals over roughly three minutes of screensaver:

- Package temp: 60 C -> **97 C** (crit 110)
- Fan: 2421 -> **5682 RPM**
- `package_throttle_count`: 638 -> **1097**

### The two 1440p windows isolate the variable

DP-3 and DP-4 both got a **2560x1440 logical** window — identical character
grid, identical font size, identical effect. The only difference is scale:
DP-3 renders 4x the device pixels and costs ~3x the CPU (303% vs 103%).

That rules out monitor count, grid size and effect complexity as the driver.
It is pixel-bound software rasterization. A single 5K display with no other
monitors attached would still cost ~300%.

## Isolating ttfx

Running `ttfx` alone into an off-screen pty at the same grid (232x60) and
`--frame-rate 120` costs **1.2% CPU**. `ttfx` is not the problem; it is cheap
regardless of framerate. All of the cost is on the terminal-rendering side.

## Why this is the default path

- `default/xdg-terminal-exec/hyprland-xdg-terminals.list` lists only `foot.desktop`
- `install/omarchy-base.packages` installs only `foot`
- `omarchy-screensaver` also supports Alacritty / Ghostty / Kitty, which are all
  OpenGL-accelerated and would be dramatically cheaper — but a stock install
  never takes that path.

## Additional notes

- `--frame-rate 120` is requested against 60Hz panels, so a portion of the
  generated and parsed output can never be displayed.
- The idle cycle re-arms, so an unattended machine repeats the ~150s burn every
  cycle rather than doing it once.

## Suggestions

Offered as options, not a prescription:

- Cap the framerate to the monitor's refresh rate, or lower the default well
  below 120 (30-60 looks identical for these effects).
- Scale the framerate down as device-pixel count rises.
- Expose the framerate as a setting in `shell.json` alongside
  `idle.screensaver` / `idle.lock`, so it can be tuned without editing a
  package-owned file in `/usr/share/omarchy/`.
- Consider skipping or simplifying the screensaver above some pixel threshold.

## Workaround

`omarchy toggle screensaver`, or set `idle.lock` close to `idle.screensaver` in
`~/.config/omarchy/shell.json` so hyprlock takes over quickly.

## System details

```
Omarchy   4.0.1-1
Hyprland  0.56.2-1
foot      1.27.0-2
ttfx      0.3.2-1
mesa      1:26.2.1-1
kernel    7.1.9-arch1-2
CPU       Intel Core Ultra 7 165H (22 threads)
GPU       Intel Arc / Meteor Lake-P [8086:7d55], i915
Laptop    Framework
Monitors  eDP-1 2880x1920@120 scale2 / DP-3 5120x2880@60 scale2 / DP-4 2560x1440@60 scale1
```