Everything is relative and in the Web usually large is quite a bit smaller than native, so here I assume “large” really meant “bigger than 2D Canvas or SVG could handle”. This example has a few 100k things [0] so you could judge by how well that works.

Not sure about the 64 bit statement, but I assume it means relative to normal 32 GL shader math. Which is definitely not “unparalleled”, but I assume better than the truncated doubles of native JavaScript or the standard shader math.

0 - https://deck.gl/#/examples/core-layers/geojson-layer-paths