# Copying / Moving Files in LAN very slow in Opus vs Explorer

**URL:** https://resource.dopus.com/t/copying-moving-files-in-lan-very-slow-in-opus-vs-explorer/30937
**Category:** Help & Support
**Created:** [December 25, 2018, 6:19pm UTC](https://resource.dopus.com/t/copying-moving-files-in-lan-very-slow-in-opus-vs-explorer/30937 "2018-12-25T18:19:16Z")
**Posts on this page:** 1
**Showing post:** 18

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### Author: ![b-s-ger](https://resource.dopus.com/letter_avatar_proxy/v4/letter/b/3ec8ea/32.png) [@b-s-ger](https://resource.dopus.com/u/b-s-ger)
#### Post date: [January 1, 2019, 5:43pm UTC](https://resource.dopus.com/t/copying-moving-files-in-lan-very-slow-in-opus-vs-explorer/30937/18 "2019-01-01T17:43:39Z")

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> [@Leo](#):
>
> What happens if you use Total Commander's "Big File copy mode"?

Horrible. Even slower than Dopus. Even if I set the buffer to something like 10240 k for different disks. Total Commander is as fast as the Windows Explorer (both directions) if I simply use the "Standard Copy method".

> [@Leo](#):
>
> Are we comparing the shell file copy speed vs everything else again, or more than two things to see if the other end is sensitive to the way the data is sent in some way?

The most simple tests is copying a Windows 10 ISO file. It's totally consistent. I copy with Dopus TO the server and then FROM the server.  
I have also tried this tip with the button to use nircmd.

> [@Copy files via the shell (Windows Explorer)](https://resource.dopus.com/t/copy-files-via-the-shell-windows-explorer/12052/7):
>
> Ah yeah... wasn't thinking.

This gives me full speed.

> [@Leo](#):
>
> The buffer size making such a difference suggests that trying more buffer sizes may find a sweet spot for the network or device at the other end. Process Monitor can show the buffer size Explorer (or TC) is using when copying to the network device, which is worth a try in Opus.

Reading this, I have now put in some ridiculous number in copy\_buffer\_size: 512 MB  
And voila, I see much better speeds. But also strange fluctuations.

 ![Dopus%20Fluctuation](https://resource.dopus.com/uploads/default/original/3X/4/7/47739b6a2ad9e9a6fc78505dfcfa8ed12e261cf6.jpeg)

> [@Leo](#):
>
> Have you tried with a standard Windows server at the other end to compare that? That is what I use, and the link gets saturated no matter which software is sending the data, as it should.

It's a Windows Server 2016 at the end.

OK, from the speed perspective, I think I reached a better speed with that ridiculous buffer size of 512 MB. I still think it's a bug in Dopus that needs to be investigated and fixed once and for all.  
If you can write me how to configure Process Monitor I can help hunt down the root cause.

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