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by charcircuit 123 days ago
That post doesn't say that it takes 16ms to create a scene and have the terminal rasterize and try and present it. That's just the budget they have. It is the upper bound they have to work with.

For example Claude Code could emit a strange symbol and if the terminal has to go and load a font from disk to be able to rasterize something that can eat into the budget and prevent the terminal from having a smooth frame rate by causing a frame drop.
1 comments
troupo 123 days ago
> That post doesn't say that it takes 16ms to create a scene and have the terminal rasterize and try and present it.

So they literally take 16ms to rasterize just a few hundred characters on screen. Of those, 11ms are spent in "React scene graph", and they have 5ms to do the extremely complex task of rendering a few characters.

16ms is an eternity. A game engine renders thiusands if complex 3D objects in less time. You can output text to terminal at hundreds of frames per second in Javascript: https://youtu.be/LvW1HTSLPEk?si=G9gIwNknqXEWAM96

> and if the terminal has to go and load a font from disk to be able to rasterize something that can eat into the budget

Into which budget? They spend 11ms "laying out a scene" for a few hundred characters. "Reading something from disk" to render something is a rare event. And that's before we start questioning assumptions about read speeds [1], whether something needs to be rendered in a TUI at 60fps etc.

[1] Modern SSDs can probably load half of their contents into cache before you even begin to see the impact on frames. Unless it's a Microsoft terminal for which they claim they need a PhD to make it fast.

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troupo 123 days ago
More on disk read speed: https://planetscale.com/blog/io-devices-and-latency

--- start quote ---

A typical random read [on a HDD] can be performed in 1-3 milliseconds.

A random read on an SSD varies by model, but can execute as fast as 16μs (μs = microsecond, which is one millionth of a second).

--- end quote ---

If you drop frames in a TUI on a HDD/SDD read for a font file (10-20 KB), you're likely completely incompetent.

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charcircuit 123 days ago
>So they literally take 16ms to rasterize just a few hundred characters on screen

Did you measure this yourself? Where is this number coming from? I am talking about a budget. Even if it takes 1ms total as long as that is under 16 ms that is fine.

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troupo 123 days ago
> Where is this number coming from?

They literally complain about that in yhe tweet I linked. That they spend 11 ms in React and only have 5ms to do the impossibly hard task of outputting a few characters on screen.

> Even if it takes 1ms total as long as that is under 16 ms that is fine.

How is it fine when you can re-render the entire terminal in microseconds (I also linked a demo for that, too), and they take 11 milliseconds just "constructing React scene"?

It doesn't matter if they take 12ms to render or 16ms. You're completely missing the point.

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