Maybe you have a BIOS setting dis-/enabled that prevents the system to run the harddrives at full speed, by using the wrong protocol, UDMA comes to mind.
Another angle: In a video showing problems with Zorin OS on 2GB RAM, an upgrade to 4GB RAM was sufficient, see video of laptop repair with Zorin OS. In other graphic-heavy distros, too, EndeavourOS, 4GB was sufficient, see video how it runs on Intel Core 2 Duo 2GHz. In other words, Zorin is evidently slow, if it uses swap files on the harddrive, because 2GB RAM was insufficient and 4GB appear to be sufficient (while no longer sufficient for Windows 11).
If nothing works: I've prolonged the lifespan of late-2000s computers with the last 32-bit versions of Puppy Linux (ISO file), specifically the ones that can be loaded into RAM as a live system.