Assistant
Online · replies stream in
You
Why does our chat UI feel slow even though responses are fast?
measure_ttftCompleted
Time to first token across the last 24 hours of sessions.
Assistant
Perceived speed is set by time-to-first-token1 and paint behaviour, not total generation time2. Stream tokens into a shell that has already painted, keep the transcript pinned while the reader is at the bottom, and reserve layout space for tool cards so nothing jumps as states resolve.
Sources
- 1Streaming SSR with React Server Components react.devSelective hydration lets the shell paint immediately while slower subtrees stream in as they resolve.
- 2Measuring Time to First Token in production vercel.comTTFT is dominated by queueing and prefill; chunked transfer keeps perceived latency flat.
AI Chat
proA composed chat section — model picker, transcript with reasoning and tool calls, and composer.
View details