Ballooning File-sizes within Templates


I’m currenting putting together some background templates together and I am perplexed as to where all the file-size is coming from. When templating 100mb of Vector Lines made in Harmony with 200mb of Bitmap Colours individually, their sizes stay the same, however when I put them together and template it, the size balloons to 1.7gb. Are the nodes worth 1.4gb?

Importing a PSD with separated layers and as a Toom Boom Original Bitmap, then templating that immediately results in 200mb. So where is the other 1.4gb coming from?

I know people can be more than the sum of their parts, how does this apply to Templates and individual layers within Harmony?