nnimap slow for message copy

[Nicolas Kowalski <Nicolas.Kowalski@imag.fr>]

Hello.

I have noticed some time ago that Pine is really faster at
moving/copying mail from an IMAP folder to another, when both folders
are on the same server. I also noticed that Gnus is really slow when
performing the same action.

The following *imap-log* shows what happens when I do a copy 'B c'
from one nnimap group to another, on the same server. The [...]
contains the message. It seems lime Gnus never uses the IMAP COPY
command. Is not there an optimization to do ?


214 UID FETCH 1247 BODY.PEEK[]
* 15 FETCH (UID 1247 BODY[] {3261}

[...]

214 OK UID FETCH completed
215 EXAMINE "mail.verimag"
* 19 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 1019817492] UID validity status
* OK [UIDNEXT 1252] Predicted next UID
* FLAGS (gnus-expire \Answered \Flagged \Deleted \Draft \Seen)
* OK [PERMANENTFLAGS ()] Permanent flags
215 OK [READ-ONLY] EXAMINE completed
216 CLOSE
216 OK CLOSE completed
217 APPEND "mail.misc" {3261}

[...]

217 OK APPEND completed
218 EXAMINE "mail.misc"
* 15 EXISTS
* 1 RECENT
* OK [UIDVALIDITY 1019818304] UID validity status
* OK [UIDNEXT 18] Predicted next UID
* FLAGS (\Answered \Flagged \Deleted \Draft \Seen)
* OK [PERMANENTFLAGS ()] Permanent flags
* OK [UNSEEN 15] first unseen message in /var/imap/kowalski/mail.misc
218 OK [READ-ONLY] EXAMINE completed
219 UID FETCH * UID
* 15 FETCH (UID 17)
219 OK UID FETCH completed
220 EXAMINE "mail.misc"
* 15 EXISTS
* 1 RECENT
* OK [UIDVALIDITY 1019818304] UID validity status
* OK [UIDNEXT 18] Predicted next UID
* FLAGS (\Answered \Flagged \Deleted \Draft \Seen)
* OK [PERMANENTFLAGS ()] Permanent flags
* OK [UNSEEN 15] first unseen message in /var/imap/kowalski/mail.misc
220 OK [READ-ONLY] EXAMINE completed
221 CLOSE
221 OK CLOSE completed