@Riquelme8
This happened to me with a wagon I was working on...  the file was about 80MB and it would save at 2.13GB...  I had my wagon in a few separate files to keep things managable..  when ever I added something new to a file it would save large...   I think it might have to do with different display render settings... being different for both objects and then bringing them both together as one.... 

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