PuTTY semi-bug sftp-slow

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summary: PSFTP, and PSCP in SFTP mode, transfer files much slower than old-PSCP.
class: semi-bug: This might or might not be a bug, depending on your precise definition of what a bug is.
difficulty: tricky: Needs many tuits.
priority: high: This should be fixed in the next release.
fixed-in: 2003-09-30 (0.54) (0.55) (0.56) (0.57) (0.58) (0.59) (0.60)

We believe this is because the SFTP and SSH-2 protocols are less efficient at bulk data transfer than SCP and SSH-1, because every block of data transferred requires an acknowledgment from the far end. It would in theory be possible to queue several blocks of data to get round this speed problem, but as yet we haven't done the coding.

Update: As of the 2003-09-30 snapshot, performance should be much improved. I believe there are tweaks that could be done to make it better still, but I'm going to declare this closed anyway.

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(last revision of this bug record was at 2005-03-10 16:36:42 +0000)