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Why Sharetru?
Platform
Windows Explorer has a static buffer size of 4096 bytes that can't be changed, in comparison to that FileZilla has a buffer size of 256 KB. The buffer size of FileZilla is thus 64 times better than that of Windows Explorer, and that explains why it capable of doing much faster transfers.
When this buffer gets filled, which goes very fast for 4096 bytes, it starts delaying loading additional data. So rather than loading a full 256 KB and sending that it only loads up to 4 KB. This takes down the upload speed as some delay is introduced.
You can change a thousand network and I/O settings but it will likely not have much effect. FTP programs have much better support as well as features such as simultaneous transfers and resuming a failed transfer, which makes Windows Explorer the wrong tool to be used for FTP. Windows Explorer isn't really made to do FTP transfers.
