As an example do this:
Export["testFig2.pdf", ListLinePlot[ RandomReal[1, 10000]]]
Insert several of these into word -- each one takes over 10 seconds to import. Now scroll the page and try to move around -- the response is terrible.
Now do this:
Export["testFigRas.png", ListLinePlot[ RandomReal[1, 10000]],
ImageResolution -> 600]
Insert this file multiple times into Word and the insert is instantaneous and the responsiveness of Word is unaffected.
Regards,
Neil