XZ is quite slow for compression when single threaded. When run in parallel it uses a significant amount of RAM. It creates some of the smallest files and is fast to decompress compared to other well-compressed alternatives.

Source: https://linuxreviews.org/Comparison_of_Compression_Algorithms

Try sudo lspci-vv. It should tell you the negotiated link speed.

It just lets you opt to see the folder size as an attribute in list view the same as you can a file in Windows or Linux. It’s more or less the same info as disk usage analyzer but without the flower and displayed inline which is useful and convenient.

“Show all folder sizes” is MacOS’ greatest innovation IMO. Honorable mention to Messages app.

Are you positive it’s not running at PCIe x4?

If they were serious about mars then they should be building very large scale very long term habitats deep in the ocean. It’s a lot closer than Mars so if something goes wrong they can improve the design faster. A trip to mars is expected to take nearly 2 years!