[Zope] Database growing fast only by viewing content?

Hi all, I am hosting a ZMS site running on Zope 2.7.3, this site is under heavy load, and the Data.fs grows like 500Mb every hour. I also get a lot of conflicts:

2004-12-08T21:40:02 INFO(0) ZODB conflict error at /live/PG/content/e899/e1425/index_ita.html (3224 conflicts since startup at 2004-12-06T16:30:01)

Since nobody is actually modifying content, and all the accesses are read-only by anonymous users, I'd like to understand what is actually written to the zodb, this also looks strange to me because read or write conflicts are always caused by an object change, but everyone is only reading content. Thanks in advance. Lorenzo