What's this about?
Claude Desktop now starts roughly twice as fast as it did a month ago. The cause is close kin to yesterday's garbage-collector fix: when the app launched in the background, its timers were throttled and the JavaScript engine dropped into power-saving mode. It now boots at full speed even while the window is still hidden.
What exactly is background throttling?
Operating systems and browser engines deliberately slow down work that isn't visible, to save battery and keep the foreground responsive. Timers fire less often, and the JavaScript engine may use a lower-performance execution mode. This is correct behaviour for a background tab playing an animation. It is exactly wrong for an app that launches hidden and is trying to finish starting up before you look at it — the system decides it isn't urgent precisely when it is.
Why is this worth noticing?
- It's the second scheduling bug in two days, after the garbage collector firing on a fixed timer. Both are cases where a general-purpose runtime optimization was wrong for this specific workload.
- Startup time is disproportionately felt. As Cherny put it, when you use Desktop every day, slow startup makes the whole app feel sluggish regardless of how fast it is once running.
- The engagement pattern says something about the product. Performance fixes drawing thousands of likes two days running suggests users had been feeling this and hadn't been able to name it.