[chrislloyd]

The communication is definitely on me! There honestly wasn't much new to say -I've been slowly ramping since early Jan just to be extra sure there's no regressions. The main two perf. issues were:

1. Since we no longer have <Static> components the app re-renders much more frequently with larger component trees. We were seeing unusual GC pauses because of having too much JSX... Better memoization has largely solved that. 2. The new renderer double buffers and blits similar cells between the front and back buffer to reduce memory pressure. However, we were still seeing large GC pauses from that so I ended up converting the screen buffer to packed TypedArrays.

[catlifeonmars]

I’m really surprised that GC is an issue at the bits/sec throughput a TUI would be pushing. At the risk of making an obvious observation: your render loop is doing way too much work for what it is producing.

[chrislloyd]

Most people's mental model of CC is that "it's just a TUI" but it should really be closer to "a small game engine". For each frame our pipeline constructs a scene graph with React -> layout elements -> rasterize them to a 2d screen -> diff that against the previous screen -> _finally_ use the diff to generate ANSI sequences to draw. We have a ~16ms frame budget so we have roughly ~5ms to go from the React scene graph to ANSI written. You're right that in theory we shouldn't have to do much work, but in practice that's required optimizations at every step.

For the GC pauses specifically, what mattered is predictable performance. More allocations == more GC == more frames where the VM is locked up seemingly doing nothing. On slower machines we were seeing this be in the order of seconds, not ms and when somebody is typing all they feel is the 1 character that's stuttering. Honestly, I was surprised about this too as GC in JS is often not something that's too impactful.

[moltar]

I think this is the main issue. When I would get into flickering mode, it appeared that the entire TUI was re-rendering on every key press. I don’t know if it’s maybe just the limitation of Ink or even terminals.