Are you having trouble when the FileZilla FTP client is slow while uploading or downloading files? By default, the FTP transfer speed between the client and the server depends on many factors: Internet Service Provider limits, FTP server or client settings, etc. In such a situation, the user can only manage the settings of its FTP client. In this guide, we will show you how to optimize your FileZilla FTP client for maximum upload/download speed.
By default, the FTP Client FileZilla is installed with minimal settings that limit the maximum allowed connection speed to the FTP server. But, if you change a few things you can speed up FileZilla and increase your FTP download speed by over 2Mb/s.
Hint. Most FTP restrictions are configured on the FTP server-side. However, some FTP client optimizations can improve the file transfer speed.
Speed up FileZilla Instructions
Step 1: Install FileZilla
Download and install the FileZilla FTP client from the official website.
Step 2: Create a New FTP Connection in FileZilla
Run FileZilla and create a new connection to the FTP host (File > Site Manager > New Site). Specify the FTP server (host) name and credentials to connect (or use Anonymous logon type).
Step 3: Speed Up FileZilla FTP Transfer by Increasing the Simultaneous Connection Number
Most FTP servers limit the maximum file upload speed for a session. But, you can upload multiple files at the same time in different FTP sessions. You can increase the number of parallel FTP sessions in your client settings and bypass this server restriction.
Go over 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.
You cannot set a value higher than 10 here because multiple concurrent sessions from your FileZilla client can put a load on the remote FTP server. In this mode, you are allowed to perform multi-threaded downloads at the same time via many concurrent connections.
This will increase the speed of your connection to most FTP servers and ensure that you are using the fastest possible speed (during our tests download speed jumped from 900KB down to 2500KB down just from changing this single option).
Step 4: Switch Client to Use Passive FTP Mode
Also, check if the Passive FTP transfer mode is used. This is the recommended mode for client computers 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 in your FTP connection properties. As you can see, three transmission 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 transfer in passive mode, so you need to allow outgoing connections on any port on your computer. Passive mode is safer for the client.
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. The main difference between the active and the passive FTP mode is the side that opens the data connection. In the active mode, the client must accept a connection from the FTP server. In passive mode, the client always initiates the connection.
If you want to change the default FileZilla behavior for a new FTP connection, go to the top menu Edit > Settings > Transfers. Under the Concurrent Transfer section, change Maximum Simultaneous Transfers to 10.
Step 5: Check Your Firewall FTP Rules
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 FileZilla FTP Client rules are enabled.
Step 6: Disable FTP Speed Limits in FileZilla
If when uploading/downloading files the transfer speed does not exceed a certain value, check if you have FileZilla enabled for the speed limit for data transfer. Go to Edit > Settings > Transfers. Check if the “Enable speed limit” option is disabled in the Speed Limit section.
Step 7: Disable Disconnection Timeout in FileZilla
In some cases, when transferring files using FileZilla, a connection timeout error appears.
Error: Connection timed out after 20 seconds of inactivity
Error: Could not connect to server
In this case, you can disable the disconnection timeout. Go to the Edit > Settings > Connection and set the “Timeout in seconds” value to 0.
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.
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.
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 issue is related to just one service or all. 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 connection speed, compare if it differs in download speed to your FTP server. The screenshot shows that the average speed of uploading files via FTP to a free service is about 3MiB/s.
Note. Do not upload your confidential files to free FTP services.
Check Your ISP Connection
If your Windows device is connected to the Internet via a Wi-Fi connection, this can also result in additional delays and packet loss during data transfer. Wi-Fi causes a lot of latency and packet loss on the local network. 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 less 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. Additional tunnels and routes can introduce a significant delay in packet delivery and file retrieval.
Try disabling proxy server and VPN connections in Windows and connect to your FTP server directly. Check if the file download speed changes.
FTP Too Slow When Sending 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 transmitting 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, before sending, you can add small files to one ZIP archive and upload only one large file to the FTP folder. Then such a ZIP archive must be unpacked on the side of the FTP server.
Check Your Antivirus
Try temporarily suspending the real-time scanning module in your antivirus. Check if the FTP upload/download speed will change. If the speed increases significantly, then your AV is using aggressive new file scanning settings, which slows down performance.