Your Encrypted Backups Are Slow Because Encryption Isn't the Bottleneck
rust
dev.to
If you encrypt files before pushing them to backup storage, you've probably assumed the encryption step is what makes it slow. That's what I assumed too. Then I looked at the numbers. On any modern x86 chip with AES-NI, AES-256-GCM runs at 4-8 GB/s on a single core. ChaCha20-Poly1305 isn't far behind. The CPU is not the problem. The problem is that your encryption tool reads a chunk of data, encrypts it, writes it out, then reads the next chunk. It's serial. The disk sits idle while the CPU work