Today · blog, October 23

CoreWeave sends only weight deltas; it's self-reported

CoreWeave self-reports that during reinforcement-learning training it sends only weight deltas and swaps them in place, with deltas about 0.14% to 0.95% the size of the full weight file. CoreWeave is a cloud provider that specializes in renting GPUs. Reinforcement-learning training keeps the model generating samples, and every weight update has to be synced to the inference service producing those samples. CoreWeave writes that in tests on NVIDIA's Nemotron 3.5 Lightning, the deltas were about 0.14% to 0.95% of the full BF16 weight file (CoreWeave, 2026-10-23). A cold start means shutting down the whole inference service, restarting it and reloading the full weights. CoreWeave writes that its fastest hot reload was about 15 times faster than the average cold-start redeployment. That was measured on 4 replicas on GB300 NVL72 racks, and it compares the single fastest hot reload with the cold-start average, two different statistics. This is a vendor's self-report from a single configuration, with no third-party reproduction. How we checked →

Concept illustration of a tablet screen split into two panels: on the left, a server unit with circular arrows below it stands beside a tall layered stack labeled WEIGHTS, an arrow runs from the stack to a second server with a dark screen, and a long arrow along the bottom points back to the left. On the right, a similar server with circular arrows sends an arrow through a thin red slab tagged DELTA toward a tall layered stack with one red layer, which a short gray piece links to a server whose screen shows a speech-bubble icon, while a bottom arrow carrying four small document cards points back to the left; below the tablet is a plaque with a blue geometric mark and the lettering COREWEAVE.

Source and checks

This item ran in the brief of Oct 25, 2026, alongside 8 other items. How we checked it, the quote checks and what was still missing that day are on that issue's How we checked page.

Cite this item

SecondSource (2026). "CoreWeave sends only weight deltas; it's self-reported." https://secondsource.io/en/product/2026-10-25-2/. Accessed access date.