EtreCheck says - "If you have an SSD your performance should always be excellent"

This is most likely due to a combination of Avast, Backblaze, and Dropbox. Your low-level performance is good, but the overall runtime is longer than 3 minutes. That suggests that lots of the normal system behaviour is running slower than it should. Your system has reported heavy CPU use from fseventsd and fileproviderd. This suggests there is low-level system contention inside the file system.

> Write speed: 2132 MB/s

> Read speed: 1867 MB/s

That does not sound too bad.

AFAIK sequential write performance between the SSD sizes in the Mac mini 2018:

128GB -> ~0.6 GB/s

256GB -> ~1.3 GB/s

512GB -> ~1.9 GB/s

1&2TB -> ~2.6 GB/s

Reads are all > 2 GB/s (2TB 2.6 GB/s)

But uninstall Avast. macOS built-in protection is all you need. 3rd party virus apps and "cleaners" cause nothing but trouble.

Post your EtreCheckPro report,

as per > How to use the Add Text Feature When Post… - Apple Community