Filezilla 3.10.3 - slow upload/download on Windows 8.1

Since the last update (to Filezilla 3.10.3) on Windows 8.1, the upload and download speeds were significantly lower and so therefore it was time to investigate why it took ages to transfer a few megabytes of files.

Why does it happen?

Because the new default for encryption in Filezilla is set to 'Use explicit FTP over TLS if available'.

The Solution

1. Open Filezilla
2. Click on the 'Site Manager' icon or click the 'File' menu and then 'Site Manager' or press Control+S.
3. On the 'General' tab there's a selection list right to the 'Encryption' setting, click on it.
4. The default setting, which is causing the slow uploads and downloads is the first one at the top, 'Use explicit FTP over TLS if available'.
5. If you want to speed things up select 'Only use plain FTP (insecure)'.
6. And, as it is stated in brackets, this type of encryption is insecure, and snoopers could intercept the data transfered.