@alfisya I don't believe Solus does any subvolume mapping automatically, it's something that has to be done manually.
The only time I saw a real speed hit myself even was when I moved ISO images around, then I saw it on my old system hit 1700-2500Mbps on my 3.0 NVME drives compared to EXT4 hitting 3200Mbps.
I'm actually curious now how it'll be on running on my new motherboard and CPU. Still not sure about only waiting 4 seconds for my login prompt from start of boot running Solus with Plasma/KDE 6. 😄