Anybody else have speed issues with external drives? I had a 1TB NVMe drive connected via USB-C to the 2017 iMac 5K, and it normally got 900/930 read write performance. With Big Sur, Blackmagic speed test starts out high, but by the 2nd test and after that, its down to about 50 MB/s write.
I tried the same drive (freshly formatted, APFS) with my M1 MBA, and same issue, but the first run is even slower at less than 600, and subsequent runs are slower still with 35 MB/s write performance.
I can't really use my external storage this way, surely there are others with the same issue?
I also have wifi dropouts on the M1 MBA, similar to the 2020 iPad Pro 12.9 on iOS 14.2.