Adiums Addressbook Settings are configured like so:
[x] Use Addressbook Images as contact symbols
[ ] Even if the contact already has a symbol
[x] Overwrite Addressbook Image with contact symbol
(probably the wording is a bit different in the en locale)
test system is running 10.5.1
The problem is, that adium overwrites the addressbook image every time the contact signs on. so even if the image didn't change, sync services marks the contact as changed in the truth database.
So every application working with contacts and syncservices will get a notification "contact x" has changed.
this leads to massive cpu load and even obsolete traffic in some situations.
in order to solve this issue adium should do something like
(pseudocode)
if contactsymbol not equal to addressbookimage : overwrite
else : do nothing
this would heavily reduce load on the truth database and thus heavily reduce load on third party applications using sync services.