I was wrong.

The first prototype worked fine with short audio clips, but everything fell apart when I tried loading recordings that were several hours long.

Memory usage exploded.

The UI became unresponsive.

Zooming was painful.

Even generating waveform peaks took longer than expected.

What surprised me most is that the actual challenge wasn't decoding audio. It was rendering and managing huge amounts of timeline data efficiently.

I ended up experimenting with Web Workers, IndexedDB caching, virtualized rendering and progressive loading strategies just to keep the browser responsive.

For those who have built browser-based audio tools:

What was the hardest performance bottleneck you encountered?

Was it decoding, rendering, memory management, or something else entirely?