Drag a layer into a another document will make the target file size huge.

Dear All,

I have a issue about file size. The canvas size is 72x60px. There is only one small rasterised image that image size is smaller than canvas size. The file size is around 1MB. However, the document size will be increased over 40MB if I drag a layer form any other documents into target file, which the layer is also small rasterised image. I found this issue is only happened when I drag the layer. If I use 'duplicate layer', the target file size will be normal and small. I need to highlight that the layer I drag is not smart object and image size is smaller than canvas size. That means the target size will not be bigger.

After drag a layer into target document and save it, the file size is extremely big. I tried to delete all layers and just leave white background. The file size is still over 40MB. I tried different layers(image and text) from different source files but the target file size is still kept big. I am thinking when I drag a layer into target file, the redundancy data is also attached into target file.

I found a solution to make target file smaller, which is duplicate all layers into new document. But I still think there should be an easy way. I was wondering if anyone knows about this issue and fix the file size easily.

Thanks a lots.

Bo