Best allocation file size for external SSD?

[superspartan]

I have a SanDisk Extreme Pro 8TB Portable SSD that I need to format. What is the best file allocation size?

My data consists of mixed files ranging from small pics, music, documents, software installers, and large 4K files

I want to format it in exFAT but not sure what is the best file allocation size for the best performance.

I tried 2048KB which is the default but my write speeds dropped from 800MB/S to 500 MB/S although the read speed was at 800 MB/S

[superspartan]

After doing many tests, I got the best speeds by setting the allocation unit size to 128K. When I set it at the default 32K, small file transfers slowed down to a crawl.