Trouble with table

i found that powerpoint tables after edit with aspose (add or remove rows) takes too much disk space after save.
i have template.ppt with tables and i fill this tables with aspose.slides (it’s realy fast!). but every table (20*16) contains about 100Kb unused information. I found this after edit one slide with one table (from aspose-generated presentation) in ms office (set left table border to bold). After saving 100-150kb space per table dissaper.
Please, give me advice how can i do it with aspose.slides.