Are you having trouble when the FileZilla FTP client is slow while uploading or downloading files? The speed at which FTP files are transferred between client and server depends on many factors: your Internet Service Provider’s bandwidth, FTP server configuration (including the server’s bandwidth, hard drive speed and/or current disk I/O), your FTP client settings, etc. In this guide, we will show you how to optimize your FileZilla FTP client settings for maximum upload/download speed.
Maximize FTP File Transfer Speed in FileZilla
By default, the FTP Client FileZilla is installed with minimal settings that limit the maximum allowed connection speed to the FTP server. By changing some settings in the FileZilla client, you can significantly increase your FTP upload/download speed.
Enable FTP Multi-threading in FileZilla
Most FTP servers limit the maximum file upload speed for a session. However, you can upload multiple files simultaneously in parallel FTP sessions. This can significantly increase the overall FTP upload/download speed in FileZilla.
Open your FTP connection settings, go to the Transfer Settings tab, and enable the option “Limit number of simultaneous connections”. Change the “Maximum Number of Connections” to 10 (by default FileZilla uses only two simultaneous FTP connections).
This way you will allow the FTP client to download or upload simultaneously 10 files in parallel threads, which significantly speeds up the overall speed when transferring multiple files.
It is not recommended to set a value higher than 10. This is because multiple simultaneous sessions from your FileZilla client can overload the remote FTP server.
You can change the default concurrent transfer settings for new FTP connections in FileZilla via Edit > Settings > Transfers. Change the Maximum concurrent transfers to 10 in the Concurrent transfers section.
Also check that there are no restrictions in this section in the Limit for concurrent downloads/upload options.
In addition, to speed up Filezilla, you can try to run a second instance of the program, which will also transfer files in 10 concurrent sessions.
The use of FTP multi-threading is effective when many small files are transferred via FTP. FTP multi-threading won’t help you if you want to speed up the transfer of a large file.
Note. To quickly download a large file in multiple threads, you can use FTP’s segmented download feature. This technology allows you to split a large file into smaller pieces and upload each piece in a parallel FTP session. Unfortunately, the FileZilla FTP client does not support segmented FTP downloads, so you will have to use another FTP client (such as iGetter, Cyberduck, CuteFTP Pro, SmartFTP Pro).
Enable Passive FTP Mode in FileZilla
It is recommended to use Passive FTP transfer mode if your computer is behind a NAT or proxy server. FileZilla automatically switches to Passive FTP mode, which is a more firewall-friendly protocol. If you have a direct Internet connection and public (dedicated) IP address, you can try to switch your FTP client to the Active transfer mode.
You can change the FTP transfer mode on the Transfer Settings tab of your FTP connection properties. Three FTP transfer modes are available:
- Active — in this mode, the client opens a socket and waits for a connection from the FTP server. This configuration will work only in the case of a direct Internet connection without NAT routers, and your firewall should also allow creating connections on all ports above 1024;
- Passive — the client cannot tell the server to select a port for file transfers in passive mode, so you need to allow outgoing connections on any port on your computer. Passive mode is safer for the client.
In most cases, the active FTP transfer mode will provide faster speeds.
Hint. There are many misconfigured FTP servers on the Internet that don’t support both transfer modes, so it is recommended that you test both transfer modes.
Note. In the active mode, the client must accept a connection from the FTP server. In passive mode, the client always initiates the connection.
Check FileZilla FTP Client Rules in Windows Defender Firewall
In some cases, Windows Defender Firewall with Advanced Security can block the FileZilla FTP transfers in the active mode.
During installation, the FileZilla client automatically adds firewall rules to accept FTP traffic. These rules allow inbound/outbound traffic associated with the FileZilla app. If one of the FileZilla ports is closed in your firewall, it may slow down your FTP speed.
Open the Windows Defender Firewall inbound rule list and make sure that the FileZilla FTP Client rules are enabled.
Disable FTP Speed Limits in FileZilla
If the upload/download speed doesn’t exceed a certain value, check that you have enabled transfer speed limits in FileZilla. Go to Edit > Settings > Transfers. Check if the “Enable speed limit” option is disabled in the Speed Limit section.
Then select Edit > Settings in top menu and go to the Transfers section. Check that the speed limits are not configured here.
Filezilla Downloading Speed Remains Slow?
If the steps described above didn’t help you and that doesn’t increase the upload or download speed, most likely you set a limit on your ISP (ask your ISP how many simultaneous connections the server supports); or on the webserver you are connecting to (if you use Filezilla FTP Server, increase the values of Internal transfer buffer size and the Socket buffer size). We have experienced hosts like GoDaddy tightly restricting their speeds on FTP.
Fix Slow FTP Transfer Speed in Windows
Additional tips and other reasons why file transfer via FTP in Windows can be slow:
Check FTP Upload/Download Speed on Other Services
Check if the slow FTP file transfer problem is related to just one service or all of them. You can use one of the free online FTP testers to check your FTP transfer rate. For example:
- https://dlptest.com/ftp-test/ — offers a ready profile file with FTP settings for FileZilla. Just download and import the FTP connection to FileZilla from the File > Import menu (https://dlptest.com/DLP_Test_FTP_FileZilla.xml).
Connect to the specified FTP server and try uploading and then downloading a large file. Measure the speed of the connection and compare it with the download speed of your FTP server. The screenshot shows that the average speed of uploading files via FTP to a free service is about 3MiB/s.
Check Your Network Configuration
If your Windows device is connected to the Internet via a Wi-Fi connection, this can also cause additional delays and packet loss during data transfer. This wireless protocol (even 802.11n, which supports high-speed bandwidth up to 300 Mbps) is not designed for frequent and heavy upload and download activities. Try using a wired (Ethernet) connection instead of wireless (Wi-Fi) one.
Also, keep in mind that most ISPs provide asymmetric Internet connections to their customers. This means that the speed of uploading files to the Internet will be several times slower than the speed of downloading files.
If your computer is connected to the Internet through a VPN or proxy server, this may also cause additional network delays when uploading files via FTP.
Try disabling proxy server and VPN connections in Windows and connect to your FTP server directly. Check if the file download speed changes.
Slow FTP Transfer when Uploading/Downloading Many Small Files
If you are copying a large number of small files to the FTP server, FileZilla (and any other FTP client) will spend a lot of time sending control commands and receiving a response from the FTP server for each file. In this case, the overall speed of uploading/downloading files from the FTP server can drop significantly.
In this case, it is recommended to increase the maximum number of simultaneous file transfers. Or you can put small files into a ZIP archive before sending, and upload just one large file to the FTP folder. Then extract such a ZIP archive on the FTP server’s side.