Page loading speed drops off

Hi,
I am using FileAway for an extranet page, with a table of PDFs which can be displayed in flightbox or downloaded.
However, now I have a few PDFs in my list, it seems that they are all pre-loaded and cached prior to displaying the page : my page loads (at first attempt) after two or three minutes !
I have tried to tweak both transient and permanent thumbnails mode, nothing changes.
I also have played with maxsrcbytes, maxsrcwidth and maxsrcheight, no results either.
I have been reading thousands of topics and found nothing…
Did anybody encounter this issue (and resolve it) ?
Thanks in advance !