How big is the logo in pixels before you insert it into your title block?
I beleive that SolidWorks saves the image as a bmp file internally in the slddrw. Bitmaps are pretty piggy. If you are starting with a high pixel count image and then window sizing it down in SolidWorks you may be moving a lot more data to your printer then you think. Could cause speed issues if your printer does not have a lot of memory for it cache. Also could be a lot of data that needs moved across your network.
Just a guess on where to look.