Inordinate delay while exiting a particular group

Inordinate delay while exiting a particular group

[Nevin Kapur]

I have an nnimap group where I route all my junk.  It has the
following group parameters:

((total-expire . t)
 (agent-predicate . junk)
 (expiry-wait . immediate)
 (expiry-target . delete))

I check this infrequently.  Each time I exit this group, it takes a
*really* long time for the expiry process to complete, something on
the order of 5-6 seconds, during which the load on my machine
skyrockets.  Normally, exiting a group takes a fraction of a second.
I can't figure out how to track this down.  Here's the result of
profile-key-sequence:

Function Name                    Ticks    %/Total   Call Count
=============================    =====    =======   ==========
re-search-forward                 1426     92.537          750
(in garbage collection)             33      2.141    
expand-file-name                    19      1.233         1399
file-exists-p                       19      1.233          698
file-name-as-directory               9      0.584         1390
format                               8      0.519          902
insert-file-contents-internal        4      0.260           11
write-region-internal                4      0.260           11
=                                    2      0.130        12573
princ                                2      0.130            3
get-buffer-create                    1      0.065           37
delete-backward-char                 1      0.065           15
gnus-agent-group-path                1      0.065          688
set-window-buffer                    1      0.065            5
check-menu-syntax                    1      0.065          592
gnus-parse-complex-format            1      0.065            2
gnus-agent-expire                    1      0.065            1
gnus-compress-sequence               1      0.065           28
read                                 1      0.065          204
gnus-dribble-enter                   1      0.065            3
when                                 1      0.065        12565
accept-process-output                1      0.065            9
prin1-to-string                      1      0.065            3
message                              1      0.065           18
string-match                         1      0.065         2214
--------------------------------------------------------------
Total                             1541    100.000


One tick = 1 ms


Any ideas as to how to debug this?

-Nevin