---
id: external-drives.why-does-copy-speed-drop-partway
url: https://storagestudio.us/faq/external-drives/why-does-copy-speed-drop-partway
category: "External drives"
subcategory: "Speed, cables and hardware"
question: "Why does my external drive's copy speed drop partway through a big copy?"
alt_questions:
  - "SSD fast at first then slow"
  - "Copy speed drops after a few gigabytes"
  - "External SSD slows down during large transfer"
  - "why does my transfer start fast then crawl"
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."
tags: ["ssd", "cache", "copy speed", "heat"]
related: ["https://storagestudio.us/faq/external-drives/do-external-ssds-get-hot", "https://storagestudio.us/faq/external-drives/why-is-my-external-ssd-slower-than-advertised", "https://storagestudio.us/faq/external-drives/why-are-many-small-files-slow-to-copy"]
applies_to: "all"
last_reviewed: 2026-10-01
---

# Why does my external drive's copy speed drop partway through a big copy?

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](https://storagestudio.us/faq/external-drives/do-external-ssds-get-hot). Long moves in Storage Studio simply take longer; you can keep working meanwhile.