Default to “do the minimum possible work per hot-path update.” Apply these checks: 1) Early-exit before side effects - If a piece of async work is no longer relevant (stale session, unmounted view, toggled-away state), return before starting the network call/timer/observer. 2) Keep props/callbacks stable during streaming - If a child is `React.memo`’d (or any memoized subtree), don’t pass freshly-created inline handlers every render. Use `useCallback` (and `useMemo` for derived values) so shallow prop comparisons remain true. 3) Don’t recreate observers/effects due to irrelevant dependencies - For `ResizeObserver`/event listeners, only depend on values actually used by the effect. If the effect body doesn’t read a dependency, removing it prevents unnecessary teardown/re-setup during frequent rerenders. 4) Throttle at the right stage + memoize expensive transforms - When throttling streaming content, throttle the raw rapidly-changing input *before* expensive parsing/transforms so the transform runs no more often than intended. - Avoid dependency patterns that create self-perpetuating timeout chains; use refs for “latest value” and keep effect deps minimal. - Even with throttling, memoize the expensive transform so it runs only when the throttled input (or other required inputs) actually change. 5) Detect changes against consistent baselines - When deciding whether to write settings / trigger refresh, compare the same effective-state lists (not a filtered list vs an unfiltered one) to avoid spurious no-op writes. Example (stable handler + throttled transform): ```ts const handleRightPanelOpen = useCallback((request: TurnOutputOpenRequest) => { if (request.kind === 'subagent') { onRightPanelOpen?.({ /* ... */ }); } }, [onRightPanelOpen]); const throttledContent = useThrottledValue(content ?? '', isStreaming); const renderedContent = useMemo(() => { if (throttledContent && source && sourceMarkdown?.transformMarkdown) { return sourceMarkdown.transformMarkdown(throttledContent, { source }); } return throttledContent; }, [throttledContent, source, sourceMarkdown?.transformMarkdown]); ``` Use this standard to review PRs that touch streaming, parsing, rendering, observers, and settings-change detection.