One application or multiple ones?

Hi experts,

I'm encountering a confusion to decide choosing one application for planning or splitting it to multiple applications. I'm sorry that this question is somehow general and hard to answer, i'm trying to specify more:

Day 1: We have 8 dimensions in a planning application and we use it to do the asset planning, expense planning and finance planning.

Day 2: We find the data volume of this application is too big, we decide to split it to 3 different ones. Fortunately these 3 applications share all 8 dimensions.

HOWEVER, I'm seriously not sure what are the pros and cons of these two decisions: One application (except rate, etc.) for all business or multiple ones?

Thanks,

Tony