Project file size grows for no apparent reason in large Production

Can anyone offer any ideas for why a project file would grow several MB a day when little to no work has been done on it?

I'm supporting a feature doc with a complex history that has now ended up in Premiere Productions and has experienced a lot of crashing, slow loading, and other bugs. I've solved a lot of the immediate issues, but have been seeing some project files grow randomly. IE I'll work for a bit on a string-outs project, adding a new sequence and making selects based on one of the other stringouts. The project only has timelines, the source clips live in other projects. The new timeline is 5-10min. I close the project and come back the next day and the project has grown by several MB. This continues every day for no apparent reason.

The size of the project file is not neccessarily a problem(yet), but I fear it is sign off some of the other problems I've been troublshooting. And seems to be escalating every day. This same thing happened before the production became unworkable and the director brought it to me.

What contributes to a growing project file size? What is different in the context of a production?

A few details about the Production:

- there was some operator error getting the project from where it once started into Productions that lead to a lot of duplicate clips living in different projects and associating to different timelines accross different version of the edit(partly a legacy of orignating as seperate projects back in FCP7, then in stand alone project in Premiere).

-extensive use of subclips

-extensive use or markers - some originally saved to XMP

-all media either pro res, or DV/DVCPRO, HD or SD

-audio media all AIFF or WAV, all 48kHz

-crashes were worst after merging many projects into Productions for the first time

-no use of warp stabalizer or other plug-ins or FX

-the director and I are cuttently working on a remote shared Production folder on LucidLink with all media stored locally on cloned drives.

I know long timelines are a major contributor to a projects file size, but I am seeing projects grow without adding new timelines or while working on only very short timelines that have no effect on size when removed. There seems to something else gonig on.