My tif files are saving HUGE. Help!

[SweetChar]

Hi ladies.
Yesterday I was saving a layout as a tif file. It gave me a warning that it was over 2GB. Why???
I always (usually) reduce my layers as much as possible since I assume the more layers there are, the bigger the file's size. I pull out any papers and anything else I didn't use. I delete layers from templates such as the template flowers, element placements, etc. Often times, I even merge a paper down to the shape that it's masked to. So, why the all-of-a-sudden huge file size? When I look at previous layouts, they range from upper 100MBs to lots of 400s - 600s.

Any ideas? Do you know if file size directly correlates to number of layers? Or how "dark" the layout is? Or how much "empty-ish" area there is? I just noticed a recent layout was at 1.26GB but one saved after that was 437MB.

Or do y'all have huge file sizes, too?
Thanks for any input.