I have on three systems encrypted LVM containing whole root and swap, so the only unencrypted part is /boot/efi. The CPUs are Intel Atom x5-Z8350 [1], Intel Core��� i5-6300U [2] and AMD Ryzen 9 3900X [3]. They considerably do differ in their performances, but interestingly, on all three machines the decryption takes 20 seconds. :-) All systems have SSD disks. [1] https://ark.intel.com/content/www/us/en/ark/products/93361/intel-atom-x5-z8350-processor-2m-cache-up-to-1-92-ghz.html [2] https://ark.intel.com/content/www/us/en/ark/products/88190/intel-core-i5-6300u-processor-3m-cache-up-to-3-00-ghz.html [3] https://www.amd.com/en/products/cpu/amd-ryzen-9-3900x