Why does WinZip unzip files extremely slowly?

Jozsef Torsan
2 min readJan 4, 2019


I downloaded an archive of our Bookmark Ninja web application project to check something and started to unzip the file. The unzipping process was extremely slow. Then I figured out what made WinZip run so slow…

A reason of the extremely slow unzipping on Windows can be Defender that runs in the background and scans each file.

This usually happens when you try to unzip a file that was downloaded from an online storage (e.g. from Google Drive) or you received it as an email attachment.

To get around this problem, follow the steps below:

  1. Create a temporary folder
  2. Move the zip file to the temporary folder
  3. In the Defender settings add an exclusion for the temporary folder
  4. Unzip the files in the temporary folder

How to add a folder exclusion in Defender on Windows 10?

  1. Click on Windows search and type “defender settings”
  2. Click on “Windows Defender Settings”
  3. Click on “Virus & threat protection” under “Protection areas” on Windows Security
  4. Click on “Virus & threat protection settings”
  5. Scroll down and click on “Add or remove exclusions” under “Exclusions”
  6. Click on “Add an exclusion” and select the folder you want to exclude

Be careful

Only use this method to avoid Defender scanning the files if you 100% trust the files you want to unzip (e.g. you were the one who zipped the files and uploaded to an online storage).

Once you finished unzipping the files it is recommended to remove the folder exclusion in Defender. You can remove an exclusion by following the above steps of adding an exclusion but at the end you click on “Remove” next to the folder.



Jozsef Torsan

Founder & software engineer. Creator of the Bookmark Ninja online bookmark manager. https://www.bookmarkninja.com/