Sandisk Extreme Portable V2 SSD speed is slower on iMac than on MacBookPro - what's wrong?

Question

USB

I bought a Sandisk Extreme Portable V2 500Gb SSD for iMac on M1 with 256Gb on board in order to use it as a fast external SSD (working with large files + offloading SSD in iMac a little).

The manufacturer claims a read/write speed of up to 1000MB
/ s . SSD connected via Type-C Thunderbolt in iMac'e The same SSD delivers up to 900 MB / s when connected to a MacBook Pro on Intel'e. What could be wrong?

Answer 1

Seems like a common problem. External SSDs are slower on M1 than on Intel
https://forums.macrumors.com/threads/usb-on-m1-mac...