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| faq_slow 2021-10-11 | faq_slow 2025-05-13 06:50 (current) | ||
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| ===== Network Delay/Latency ===== | ===== Network Delay/Latency ===== | ||
| - | Network delay/latency affects particularly %%SFTP%%, as it is a packet oriented-protocol. When trandferring, the SFTP client (WinSCP) sends a read/write request to the SFTP server, waits for a response; and repeats, until the end of the file. | + | Network delay/latency affects particularly %%SFTP%%, as it is a packet oriented-protocol. When transferring, the SFTP client (WinSCP) sends a read/write request to the SFTP server, waits for a response; and repeats, until the end of the file. |
| Even if your connection is fast, if the server is far away (or slow), it takes a time for the response to arrive back. If the client spends this time uselessly waiting, your transfer speed will be low. | Even if your connection is fast, if the server is far away (or slow), it takes a time for the response to arrive back. If the client spends this time uselessly waiting, your transfer speed will be low. | ||
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| See also [[wp>Bandwidth-delay_product|Bandwidth-delay product]] on Wikipedia. | See also [[wp>Bandwidth-delay_product|Bandwidth-delay product]] on Wikipedia. | ||
| - | In case the speed is throttled by a connection latency, it may help if you use [[scp|SCP protocol]] instead of [[sftp|SFTP]]. %%SCP%% is less affected by the latency. In this case, it may help if you turn on [[ui_login_ssh#protocol_options|compression]]. Toggling //[[ui_login_connection|Optimize connection buffer size]]//, in either way, can help too. | + | In case the speed is throttled by a connection latency, it may help if you use [[scp|SCP protocol]] instead of [[sftp|SFTP]]. %%SCP%% is less affected by the latency. Though we got reports of exactly opposite behavior too (SFTP being faster than SCP). When connection latency is the bottleneck, it may additionally help if you turn on [[ui_login_ssh#protocol_options|compression]] (though that will have small effect if you are transferring large media files, which are compressed already). Toggling //[[ui_login_connection|Optimize connection buffer size]]//, in either way, can help too. |
| An underlying TCP protocol can suffer a similar problem too. In which case it will affect all other protocols, including SCP, FTP, WebDAV or S3. | An underlying TCP protocol can suffer a similar problem too. In which case it will affect all other protocols, including SCP, FTP, WebDAV or S3. | ||
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| If WinSCP started being slow suddenly, check if you did not [[ui_pref_logging|enable logging on //"Debug"// level]] inadvertently. | If WinSCP started being slow suddenly, check if you did not [[ui_pref_logging|enable logging on //"Debug"// level]] inadvertently. | ||
| + | |||
| + | ===== [[transfer_queue]] Parallel Transfers ===== | ||
| + | When comparing batch file transfer speed of WinSCP, note that it by default transfers all files sequentially using a single connection. While some other clients use multiple connection by default. If you prefer, you can [[transfer_queue|transfer files using multiple parallel connections]] in WinSCP too. | ||