External drives · Speed, cables and hardware
Why does my external drive's copy speed drop partway through a big copy?
Short answer: Many SSDs write into a fast cache first and slow down once it fills, and drives slow themselves when warm. A copy that starts fast and settles lower is normal; a crawl or disconnects point to a cable, connection or heat problem.
Many SSDs write very quickly into a fast cache area first, then slow to their normal speed once that cache is full — so a large copy starts fast and settles lower. A drive that gets warm may also slow itself to protect the hardware. Hard disks are naturally a little slower toward the end of the disk.
None of this is a fault. If speed collapses to a crawl, or the drive disconnects, check the cable and connection and see whether it's normal for the SSD to get hot. Long moves in Storage Studio simply take longer; you can keep working meanwhile.