Leaving gnus is slow

[andreas.koenig.gmwojprw@franz.ak.mind.de (Andreas J. Koenig)]

Leaving gnus takes between 5 and 10 minutes on a fast and otherwise
sane and well behaving machine. Other gnus operations are as fast as
they have always been. The slowdown became noticable a few months ago,
then became annoying a few weeks ago. strace shows the same pattern
several 10000 times:

  gettimeofday({1132127555, 814214}, NULL) = 0
  gettimeofday({1132127555, 814633}, NULL) = 0
  setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 1000}}, NULL) = 0
  sigreturn()                             = ? (mask now [])
  --- SIGALRM (Alarm clock) @ 0 (0) ---
  gettimeofday({1132127555, 824205}, NULL) = 0
  gettimeofday({1132127555, 824611}, NULL) = 0
  setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 1000}}, NULL) = 0
  sigreturn()                             = ? (mask now [])
  --- SIGALRM (Alarm clock) @ 0 (0) ---
  gettimeofday({1132127555, 834211}, NULL) = 0
  gettimeofday({1132127555, 834616}, NULL) = 0
  setitimer(ITIMER_REAL, {it_interval={0, 0}, it_value={0, 1000}}, NULL) = 0
  sigreturn()                             = ? (mask now [])
  --- SIGALRM (Alarm clock) @ 0 (0) ---

My ~/.gnus.registry.eld file looks a bit largish to me:

-rw-rw-r-- 1 k k 18651823 Nov 16 08:59 /home/k/.gnus.registry.eld

My largest overview files are:

-rw------- 1 k k 4366389 Nov 16 08:14 /home/k/Mail/subversion/.overview
-rw------- 1 k k 4879095 Aug 31 04:41 /home/k/Mail/svg-developers/.overview
-rw------- 1 k k 7715045 Nov 16 08:07 /home/k/Mail/junk/.overview
-rw------- 1 k k 9153921 Nov 16 09:03 /home/k/Mail/pause/.overview

Any suggestions where to have further looks and how to pull this
straight again?

I'm running current CVS.

Thanks,
-- 
andreas