Modal adds memory snapshots to cut serverless cold starts by 2.5x

Modal introduced memory snapshot restore for its serverless GPU container runtime, which it says makes cold starts about 2.5x faster than standard container startup. A Stable Diffusion inference Function that normally takes around 13 seconds now restores in 3.5 seconds, and a simple import torch program drops from roughly 5 seconds to about 1.05 seconds at p50 and 0.69 seconds at p0. Snapshots are built on gVisor's checkpoint/restore and are created on demand, with automatic fallback to a standard container startup when a restore fails; GPU state is not yet saved, so it must be rebuilt after restore.