Hi Luz,
Is it essential to save the graph image to a disc file before appending it to the report - it might be a little quicker if you appended a control image directly to the report (but this might not suit you needs, as I see you are also cropping the image size, or the report might be an HTML type).
I notice that you have no "data flow dependency" between the image writing to disc and the reading back of the image into the report, so theoretically your program could attempt to read the file before it was written - I would recommend that you wire the "error cluster wire" through the "Write PNG file" VI first, then connect it on through the "Append image to report" VI to eliminate this possibility.
Sorry if this isn't much help - but writing compressed images to disk, then reading back is always likely to be relatively slow.
Regards.
Mark.
