The key output order is start -> end. The browser cannot handle other JavaScript tasks while the stack is busy.
The page, request, or runtime feels stuck because one piece of work monopolizes the event loop. Chunk work, use Web Workers, or move heavy calculations off the main thread.
Doing large CPU work directly in a click or render path.
Move heavy work off the hot path, chunk it, stream it, cache it earlier, or run independent work in parallel.
const work = items.map(loadItem); const results = await Promise.all(work);
The console lane proves the visible order: start -> end. The active line and queues show why source order changed.
Record blocked time or request duration before and after the fix; the event loop should stay responsive while work completes.
Related cases
Continue with nearby confusion while the mental model is fresh.
microtask flood
Long microtask chains can delay rendering, timers, and input responsiveness.
sequential vs parallel API
Dashboards, profile pages, and search screens often benefit from parallel loading.
debounce concept
Autocomplete, resize handlers, and validation often use debounce.
Was this clear?
This stays local for now. It helps you track where the product still needs sharper cases.