Optimizing Vercel Sandbox snapshots

This post details performance optimizations for Vercel Sandbox's filesystem snapshot restore process. Key improvements include parallelizing S3 downloads using the `Range` HTTP header and the AWS Go SDK's `transfermanager` API, parallelizing decompression across multiple goroutines, and streaming S3 download streams directly into decompression to eliminate intermediate disk writes. Additionally, a local NVMe disk cache using LRU eviction was implemented to store decompressed `.img` files, significantly reducing restore times for frequently used snapshots and achieving a 95% cache hit rate.