dissel
Cyborg Agent
HDD will always be a bottleneck, try to copy some large files(preferably 1gb+) from ssd to ssd to see how much speed you get. Btw you have 2 internal ssd(120gb & 250gb) so how you manage with hdd.
I got only one SATA port as internal which occupied by Samsung 250GB SSD Win10.
I got two ADATA 120GB SSD for Linux installation which till now (as you solved the problem a weeks ago) used as external USB installation from the one 3.0 USB port of the laptop.
I got 500GB laptop's original HDD laying around,I Just open the caddy and swapped and perform the DATA transfer test.
*i.imgur.com/rhxCRZv.jpg
Anyhow can't perform the SSD to SSD data transfer test, as Win10 don't see the drive and the Ubuntu 20.04 or Budgie can't perform a write in the windows installation.....that 250GB Win10 drive auto mounted - read eanbled but can't writable, tried almost all guide but looks like windows locked the drive due to added security.