Extremely slow opening of Office files through SMB

New Contributor

Dear all,

The following question I raised before on the Office forums. I have been redirected here as they found it is likely a storage/server problem instead of an Office problem. I am encountering this problem already for some weeks and I cannot seem to find the cause. So maybe there's someone who could help me?


The problem is that some Office files, located on an SMB share on a Windows 2019 Standard Server, open very slow (sometimes it takes as much as 5 minutes for 100kb file). The problem started with one user and now it's multiple users who encounter the problem, however, I have not been able to replicate the problem on a test machine. It affects user working on desktops who logon to the domain as well as local user who directly mount the SMB share. Users are working on either Windows 10 1909 or 2004, fully up-to-date and using Office 365 Business. I have tried to following things:

  • I tested many files but it only affects some files, mostly Excel files.
  • When I move the affected file to another location on the same SMB share, the problem persists.
  • The sluggishness only occurs the first time, the second time it works as expected and only when the files are opened from Explorer.
  • The same files, which takes minutes to open from Explorer, open instantaneously when opened from Excel (recent files).
  • When I copy such a 'slow file' to the local drive of the users' pc, is always works as expected.
  • When I mount the smb share with the same credentials on another pc, there's no problem.
  • When I create a new local account on a pc that's affected, and mount the smb-share with the users' credentials who encounters the problem, it works as expected.
  • Opened task manager while waiting: cpu/memory/ssd utilization is all fine. There are no program's with more than 5% cpu utilization.
  • Tried with 'allow caching of share' in Windows Server 2019 on and off. No effect.

To me it seems some kind of Windows Explorer issue or another process that is slowing down the opening, not Excel itself. This is because the Office splash-screen isn't shown during the waiting and as soon as the Office splash-screen is shown, it means the waiting is over and the file will be open in a second. Also, when opened from Excel, the speed of opening files is as expected.

I very much appreciate your thoughts! Thanks in advance.



7 Replies

Anyone? Or someone experiencing the same problem?

@ComputerlabWe are also facing the similar issue with all MS Office file opening slow from network share.

We have windows server 2012 R2 and Office 2010 and 2013 with all updates.


After trying different settings or solution on client side including creating new local users and mapping drive as you mention. But same problem. Then we have build the a test server and created a share. Its working smoothly.


I think issue is with the server only not at clients. And I dint want to rebuild the server right now because of downtime issue.


Have you found any workaround, please share!!

@Computerlab years ago i can remember, that with office 2010, we had the same issue.

We found in the programs and feature a microsoft offce 2010 file checking tool installed (maybe with an office update). I don´t know exactly the correct name, but if you look in to programs and feature it is obvious.

After deinstallation it worked like expected.


Hope this helps.


@Rene_Gross Hi


Is that Microsoft SharePoint Foundation Support?


We have tried to remove above feature but still facing the same issue.

@Kushal1 in our case there was no sharepoint involved.

This is, what i mean: https://social.technet.microsoft.com/Forums/office/en-US/32887181-2d25-4941-b527-6f223e8b88b0/how-to...


"Office File Validation Add-In" is the name of the tool. It comes with windows update but stays in programs and feature. ( we have got this only with office 2010, not with o2016 or later)



Another possibility found here: https://docs.microsoft.com/en-us/office/troubleshoot/performance/office-slow-or-stop-responding


Maybe your network connection has problems and this could help.


But again, in our case there was no sharepoint in conjunktion with that.

@Rene_Gross Thank you for your response!!

I think this office validation Add-in, now integrated as Protected View. We have already tried to disabled it.

Also tried to disabled Micro, Add-in, ActiveX added network location in Trusted location. etc


And tried the registry settings as well. But still having the same problem.


We have also tried to remove the Office using removal tool and installation.


I think this is something to with server. We have tried to remove antivirus. disabled firewall, adding entry in host file, disabled NetBIOS, disabled Caching . but no luck. But same things are working on newly build server.

@Kushal1 I also have similar problems and I also think that problem is in server side. Even notepad opens very slowly files from network share. File server is W2K12 R2 Std 6.3.9600 N/A Build 9600