Optimization of SSD/HDD space allocation and loading time (423% faster with only 16% on SSD) - OFF TOPIC useless comments: "just install everything on SSD"

I don’t believe I have a solve for your question, but related to it, here is a topic about this you might want to check out to see if you agree with:

Support mounting compressed archives in the VFS (Virtual File System): save up to 95% disk space and hours of loading time (accumulated per year) - Self-Service / Wishlist