I am running into the same problem where I am converting a large number of word documents to pdf using aspose words and I am finding that the pfd files are on average almost 100k or twice as large at the source word document.
I did a couple of examples of converting with aspose and then converting the same file by saving it through word and the aspose files are significantly larger.
Three tests are:
|Doc Desc||Sourc doc||Aspose pdf Convert||Word to Pdf Convert|
|Small number of words||9KB||27KB||3KB|
|13 pages of text||23KB||222KB||159KB|
|Text and embedded||20,830KB||6,883KB||1,153KB