It seems an SSD harddisk for root and custom non-user partitions/directories uses way less power than a traditional harddisk. /, /var and /usr are used often. Using a traditional harddisk for home and /usr/local has negligible consequence.
I realize then, that my old hardisk may have been bad. It always shut down my computer, even after I heard a car go by, or heard a vacuum cleaner nearby be turned on. The vacuum and computer using up a lot of power tripping the circuit breaker makes sense. The car going by, maybe a coincidence, as if electrical interference, caused something that was either faulty or power intense to make my computer lose power and reboot.
Another one is to get a motherboard of the most efficient family with its CPU's when the old motherboard goes bad. If the CPU on an older motherboard is 32 bit, upgrade that to a compatible 64 bit on that same board. AMD's IIRC Ryzen is more powerful and less power consuming than previous Intels and other AMD hardware. Previous AMDs were less efficient than Intels. I don't know if Intel has recently surpassed AMD. Make that motherboard last, by cleaning out dust, and upgrade the CPU as needed.
Using dual RAM in the correct slots, to make use of maximum bus width.
Using RAM filesystems for building ports and the kernel. Using that with harddisk space to make up for anything that potentially surpasses available RAM.
Another thing, is removing bloat that usually comes with ports that are based on Linuxisms. A lot of that has been done, but it gets more difficult to find as time goes on.
Then, I kept having to rebuild ports, and the build process broke down after over 14 HOURS for ports that needed GCC. Eventually, I made a temporary Makefile, saving the original, to make this port use LLVM/CLANG instead of GCC. This and other ports that needed GCC at that time built in 5 MINUTES without error by changing the dependency to the compiler in base. For comparison, LLVM/CLANG takes 4 hours to build. For GCC, it was pulling in operating systems of dependencies, like ALSA, every single sound system, graphics system. I mentioned this to the port maintainers, and they fixed GCC to compile in a reasonable amount of time. Linuxisms are a colossal waste of time and energy. There's still a similar flaw today in Ports that use GECKO to rebuild the latest LLVM/CLANG, even when there's no vulnerabilities. All it needs for a few ports needing GECKO and for video drivers is the build utils to be upgraded, not the entire LLVM/CLANG.
Custom building a kernel is another one, but probably minor. Rebuilding the world isn't necessary, which is more trouble than it's worth.
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