From tap to menu in about two seconds
How a cold start on the test phone, an iPhone 17 Pro Max, went from about seven seconds to about two — and what was slowing it down.
From the developer 2 min read Milestone date: Posted
A cold start is the launch you make when the game isn’t already in memory: the first one after installing, or after the phone has closed the app in the background. On 5 October it became much faster. On the iPhone 17 Pro Max we test on, the main menu now appears 2.1 seconds after the tap, where it used to take 7.1–7.3 seconds, and the first match starts 0.75 seconds after you choose to play.
What was slowing it down
A 3D game draws everything with small programs for the graphics chip, called shaders. Compiling them takes time, so VELTRAIL prepares them in advance and ships them ready to use. On the iPhone, though, the prepared shaders weren’t being found. The game looks them up under a key calculated from the project settings — and two of those settings have different values on a phone than on the Mac where the shaders are prepared. Different key, no match, so the phone quietly compiled everything again on the first launch.
The fix itself was small: the project now pins those two settings to the phone’s values, so the key comes out the same on both sides. Nothing changed in how the game looks on the phone.
Before and after
- from the tap to the main menu
- 7.1–7.3 → 2.1 s
- from choosing to play to the first match
- 0.75 s
- the longest single frame
- 4.5 s → 0.30 s
- shader programs compiled on the phone
- 21 → 0
The longest frame matters as much as the total. Before the fix, the screen could freeze for four seconds or more right before the first match. A frozen picture looks like a crash even when it isn’t one, and the first seconds of a new game are exactly when a player decides whether to stay.