[Dovecot] performance problems with IMAPS

[Linda Walsh]

Timo Sirainen wrote:
> On 10.5.2011, at 22.45, Linda Walsh wrote:
>
>> I've noticed this before and wasn't sure of the problem -- sending large files from FF.
>
> What is FF?
Sorry, meant TB (Thunderbird, 2.x), FF=Firefox, BTW, braino-confusion.....
>
>> I tracked it down, and the problem is in dovecot when it is saving the mail to my 'Record' (Outbox)...
>
> So when IMAP client is sending a message to Dovecot?
>
>> It's saving the file in tiny chunks....
>>
>> Looking at a few, I see:
>> 4148 bytes
>> 2116 bytes
>> 1604 bytes
>> 692 bytes
>
> Isn't that the client that is sending it in small pieces then? How did you measure those bytes?
Using wireshark.   It **could** be the client, but it's hard to see the 
client doing
anything other sending doing a large scale 'save message' to the 
mailbox, but you're
right, it could be a fault of the client, considering how poorly TB is 
written.  It's gotten
worse with TB 3.x though with performance there really bogging down my 
machine in terms of
local disk-space consumed.   As you may be aware, TB3.x ignores the 
entire premise of
IMAP in storing messages on the server, trying to make copies of all 
messages, locally.

With my users running with roaming profiles, this easily adds over 1GB 
of locally cached
mail to each profile that needs to be copied to and from a server each 
time a user logs in
or out (creating huge lag times for login/logout).