If you can download the full chain in 10 minutes, how long does it take to validate? Well once it's downloaded, the full chain can be validated concurrently, and it's all read. So as long as the SSD/RAM can keep up, it's limited only by CPU count. We already run validation at 100% CPU on 64 cores. While shani and other local optimizations can help, it's really just Moore's Law at this point.