Can someone explain to me why copying some files (10 to 20 folders with average 6 files of 5MB) takes so long - about an hour.

I'm downloading some free music from www.jamendo.com. These are zip-files and so I open two explorers, one with the folder containing the zip-files, the other with my 2GB SD-Memory card where I create a folder with the bandname and a subfolder to store the mp3's. Then I unzip the files with the first explorer an drag them to the target folder in the second explorer.

I'm working through all the zip-files each after the other and after the third folder Vista is creeping, showing me some horrible estimating times for copying... I'm going on with my tasks and Vista freezes the mouse pointer from time to time. I arrange the file copy windows so that a can see the progressbar of all the copy-processes and I'm wondering whats going on.

Any suggestions?

  • Can you tell me what is the speed of the SD card. It should say "*X" or "Class *" (where * is a number) on the SD card if the speed is rated. – Adisak Feb 27 '10 at 0:19

i arrange the smal copy-windows so that a can see the progressbar of all the copy-processes

This sounds like you were copying several folders at the same time which is not good especially for slow devices like SD cards. You should copy one folder after the other.

  • +1 This behavior is not unique to windows. You can kill the copy performance on any OS doing this. – DaveParillo Oct 20 '09 at 14:43
  • Moreso, it's a hardware thing - nothing any OS could avoid. – Phoshi Oct 20 '09 at 14:56

Let's take a look at your numbers: 20 folder * 6 files * 5MB = 600 MB.

Speed of HD cards is either measure by 1X/2X/4X/etc (where X = *150kb/s) or by class. Class 2, 4, and 6 are the most common

 Rating    Write Speed    SD Class
   6x         0.9         n/a
  10x         1.5         n/a
  13x         2.0         2
  26x         4.0         4
  32x         4.8         5
  40x         6.0         6
  66x        10.0         10
 100x        15.0         15
 133x        20.0         20
 150x        22.5         22
 200x        30.0         30
 266x        40.0         40
 300x        45.0         45

Without write caching and with write verification on, writes under Windows usually occur right around 1/2 the rated speed of the card. (You can turn on "optimize for performance" rather than "optimize for removal" in the hardware options to get better speed out of the card but then you need to manually "Safely Remove Hardware and Eject Media" from the system tray icon).

Therefore if you have a Class 2 (13X) SD card, you can expect the 600MB copy to take a minimum (600MB / 2.0MB/s) * 2 = 600 seconds. This is around 10 min.

If you have a 4X SD card, it will take over 30 min and a 2X SD card will take over 1 hour.


There was an issue with slow file copying on Vista.

Have you patched with the latest service packs ?

Also, if it's really a major issue, you could look at migrating to Win7 ?


  • This was over networks, rather than on local drives. – Phoshi Oct 20 '09 at 14:26
  • @Phoshi: Vista can be slow starting to copy on local drives as well if there is a large number of files. In this case though, it seems as if there is a large amount of data but a relatively small number of files so that should not be the case. – Adisak Feb 27 '10 at 0:24

SD cards are slow. To them, your HDD is a raging beast, your unzipping happens many orders of magnitude too fast for it to bottleneck.

Basically, you're asking too much of the SD cards. Copy one thing at a time, they're really not built for such things.

On the progressbar and estimated time, it's... not often correct. Ignore it :)


I know that this job is killing the performance (on every OS). I'm wondering if it is not possible to detect the bottleneck an serialize the copy-jobs automatically?

What about the defragmentation on the target? Or is this no issue because to copy-process captures the needed space in the target-drive for a given file before the transfer starts?

You see, a simple copy and there are a lot of programming questions behind it.

Peace Ice

  • There'd be no point, there's no inherent slowdown in copying a lot of files - as in, it'll take the same total time. Nothing that can be done to speed that up. – Phoshi Oct 22 '09 at 8:40
  • I agree, if there really is a bottleneck anywhere. My Vista is fully patched, by the way. Thanks for all replies. – Ice Oct 22 '09 at 16:37

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