Tagged PDF file created using iText7 is huge in size when compared to other PDF creation API.is there any workaround to reduce that?

I have created a Tagged PDF file with 10k pages,using iText7.The file size is atleast 3 times larger than the same file created using pdfbox API.I have already set WritterProperties.setFullCompressionMode to true.is there anyother workaround to reduce the file size further?