[Dovecot] Significant performance problems

[Rick Romero]

  On 10/6/2010 7:41 PM, Chris Hobbs wrote:
>  On 10/6/10 5:22 PM, Timo Sirainen wrote: login_processes_count: 20
>> Probably could use less then 20.
>>
>>> login_max_connections: 64
>> And this could be higher. In general you should have maybe 1-2x the 
>> number of login processes than CPU cores.
> Since this is in a virtual environment, I went ahead and ramped up the 
> number of CPUs to 4, since I have the processors to spare.

Is your disk a virtual disk as well?  Have you checked performance?  
Something like:
| hdparm -tT /dev/sda|

On a ZFS RAID 10 of 10 7200RPM SATA drives, I get about 100MB/s

At work we have an EMC SAN, and I get like 350MB/s on that beast - but 
if this is just a vhd on a Windows box, that could be an issue..

Rick