If you ever plan to use any of these older PCs: Disable Spectre and Meltdown mitigations! As a bonus you should also remove CPU microcodes from the BIOS/UEFI and make sure that no microcode is loaded via software.
The performance gain is huge if done correctly. There is no need for these mitigations on homelabs.
The performance gain is huge if done correctly. There is no need for these mitigations on homelabs.