Conseiller d’écran
Gratuit à consulter, Pro pour modifier
Montre à quel point WindowServer travaille pour dessiner vos écrans, et propose des changements qui peuvent en rendre une partie.
The problem
If your Mac drives an external display, WindowServer, the macOS process that draws every window on every screen, can use a noticeable share of the CPU. You may see it near the top of Activity Monitor and have no idea what to do about it.
The causes are mostly settings. A scaled resolution makes macOS draw a bigger picture and shrink it to fit. A high refresh rate means more frames to draw. Each extra display adds its own picture. Hedroom reads what your displays are doing and tells you which of those applies on your Mac.
How it works
- Read. While the Display advisor is open, Hedroom reads WindowServer's CPU as a share of one core, at most every 5 seconds. If it cannot read it, it says "Unavailable" and shows no number, never a zero.
- Look at each display. Its resolution, its refresh rate, and whether macOS is drawing more pixels than the panel has and scaling them down.
- Tip only from data. Tips come from what it reads: a scaled mode, a refresh rate above 60 Hz on an external display, three or more displays, or Reduce Transparency. Each carries an impact such as "up to −N% CPU", a ceiling worked out from how many pixels per second would no longer be drawn. When it cannot estimate, it says "No estimate".
- Try it, with a safety net. Try it changes one display's mode. You have 15 seconds to press Keep or Undo. Do nothing and the old mode comes back.
- Measure. After Keep, Hedroom measures WindowServer for 5 minutes and writes a receipt. The change lasts until you log out.
What you will see
The screen shows WindowServer's live CPU with one sentence that follows the data ("WindowServer is light right now." when it is under 5%), then a card for each connected display. A scaled display shows the picture macOS draws as a dashed frame around the one you see, with an "Extra work" chip. Below are the tips, biggest first, each with its reason, an impact chip and a button: Try it, or Open Settings for Reduce Transparency, which Hedroom never flips for you. When there is nothing to change it says "Nothing to change."
After you press Try it, a sheet counts down from 15 seconds with Keep and Undo; Esc undoes. Once you keep a change, it says Hedroom is measuring for 5 minutes and that the change stays until you log out.
A worked example
Example, not real data
A scaled external monitor
Say you have a 4K external display set to "Looks like 2560×1440". macOS draws a 5120×2880 image, then shrinks it to fit the panel, so WindowServer does extra work. The advisor shows the dashed frame and a first tip: use the mode that draws exactly the panel's pixels, with its ceiling.
You press Try it. The display changes, you judge whether the result is comfortable to read, and press Keep. Five minutes later the receipt compares WindowServer before and after. If the drop is smaller than Hedroom can tell apart from normal ups and downs, it says "No measurable effect." and you can press Undo.
Details and limits
Ce qu’il fait
- Lit le CPU de WindowServer, en part d’un cœur, tant que l’écran est ouvert. S’il ne peut pas le lire, il indique « Indisponible » et n’affiche aucun chiffre.
- Affiche la résolution et la fréquence de rafraîchissement de chaque écran, et si macOS dessine une image plus grande puis la réduit.
- Ne donne des conseils qu’à partir de ce qu’il lit : un mode mis à l’échelle qui dessine plus de pixels que la dalle n’en a, une fréquence supérieure à 60 Hz sur un écran externe, trois écrans ou plus, et Réduire la transparence.
- Essayer modifie le mode d’un écran. Vous avez 15 secondes pour appuyer sur Conserver ou Annuler ; si vous ne faites rien, l’ancien mode revient.
- Après Conserver, mesure WindowServer pendant 5 minutes et rédige un reçu.
What it will not do
- Changer quoi que ce soit avant que vous n’appuyiez sur Essayer.
- Rendre un changement permanent. Même après Conserver, il ne tient que jusqu’à votre déconnexion.
- Basculer Réduire la transparence à votre place. Ce conseil ouvre Réglages Système.
- Promettre un pourcentage. Les chiffres d’impact disent « jusqu’à » et sont des plafonds, pas des prévisions.
Limits
- De petites baisses réelles apparaissent souvent comme « Aucun effet mesurable » sur le reçu. C’est le reçu qui est prudent.
- Un mode inférieur à la résolution native de la dalle peut rendre le texte flou. Hedroom le précise dans le conseil.
- Si Hedroom plante pendant les 15 secondes, le mode non confirmé revient au prochain lancement ou à la déconnexion, pas immédiatement.
Gratuit ou Pro
La mesure et les conseils sont gratuits. Essayer fait partie de Pro. Annuler n’est jamais verrouillé.
Try it changes your display, which is why it, and only it, is Pro.
Questions people ask
Could it leave my screen in a bad state?
Every change has a 15-second Undo, and a change you do not confirm goes back by itself. Hedroom writes a small journal before changing the mode. If it crashes during the 15 seconds, the unconfirmed mode comes back at the next launch or when you log out, not at once.
Does it need any permission?
It asks for no admin password. It reads and changes display modes through the same system calls any app can use, and reads WindowServer's CPU with the system's own ps tool.
Does looking cost battery or CPU?
It reads WindowServer only while the screen is open, at most every 5 seconds, and every 10 seconds while a display-change receipt is measuring, about 6 to 16 minutes. Each read is one run of ps, which took about 20 milliseconds of CPU on the Mac it was checked on.
Will it change my displays by itself?
Never. A display change needs your click on Try it. No rule or schedule can do it.