Toggling datacenters, dams, or submarine cables off only set `show = false`
on their data sources. Cesium's DataSourceDisplay still walks every
visualizer of a hidden source each frame, and the ~11.5k hidden entities
(hundreds of MB) stayed resident, so the whole scene rendered ~2x slower
for the rest of the session after a single on/off round trip (owner field
test 2026-09-13).
disable() now removes the data sources from the viewer and drops the built
records; the parsed dataset (NDJSON features / TeleGeography JSON) is cached
so enable() rebuilds without a refetch or re-parse. A disable that lands
while a load is in flight releases the finished build instead of parking it
hidden. destroy() clears the cache.
Measured with a headful Chrome harness (flights+military+satellites on,
camera rotating, 250-frame windows), before -> after:
- entities resident after OFF: 11,537 -> 0
- DataSourceDisplay.update per frame after OFF: 1.09 ms -> 0.02 ms
- scene.render per frame after OFF: 13.9 ms (control 6.6 ms) -> 5.2 ms
(fresh baseline 5.0 ms in the same run)
- JS heap 30 s after OFF: 1.6 GB and climbing -> 342 MB after GC
Tests: the GeoJSON lifecycle and cables suites assert disable leaves zero
sources/contexts and re-enable rebuilds with fetch called once.
Bilawal Sidhu