Tag

performance

3 posts

verification

5 min read Jul 15, 2026

Verified only where the bug showed: a hot-path fix that shipped a zoom-in regression

A WebGL2 flicker fix (#1139) was render-parity-verified on exactly one scenario — the zoom-OUT hold-tiles case that reproduced the original flicker, retained-content 0.19 → 0.79 matching WebGPU — and never on zoom-in or per-frame cost. It shipped an unmemoized per-frame classifyTile run twice per tile plus synchronous uploads, and stuttered with progressively-black fills on a Seoul zoom-in. Reverted 36 minutes later (#1140). A hot-path fix must be verified in its worst regime, not the one that showed the original bug.

performance webgl2 rendering

performance

6 min read Jul 13, 2026

The map that downloaded the world

A static map view produced 10+ MB/s bursts and a warm phone. The render loop was innocent, our first probe fabricated a '93 duplicate requests' finding, and the real villain was the availability feature that keeps fast-pan from blanking — politely fetching an 85-tile, 33 MB world pyramid on every load and pinning it against eviction forever. Same view after the fix: 35.33 MB → 6.27 MB.

networking debugging tiles

testing

8 min read Jul 11, 2026

A gate you have never watched fail is decoration

We broke instanced batching on purpose to watch a brand-new CI gate go red — 100,000 draw calls — before trusting its green. Why new gates need a demonstrated failure, and why this one asserts dc(10k) === dc(100k) instead of pinning an exact count.

performance ci