When reusing a psd file, in this case flyer template, saving psd/jpeg files is slow

I am using a template for a page in catalouge/flyer. Recently I discovered a issue when I'm saving psd/jpeg file. When i save a newly created psd file, for example 1,5 GB file size, and when i export it as JPEG(max quality), the export size is 5 MB, but when i save a file thats lets say 700 MB and export it as JPEG(max quality) the JPEG file is 150+ MB. The template that i have created and I'm reusing contains only guidlines and a layer of white background. When i save the document with only white background i get a file thats 214 MB(only white background).

My suspicion is that "metadata" is the problem, but i don't know how to delete the "metadata" data.