that file has a LOT of very small line segments, all those little corners are tiny line segments.... all contributes to the processing time.
also, all parts of the drawing have to be examined before cutting, with everything outside the safe cut area being looked at but disregarded when it comes to Gcode output.

however, your settings are contributing as well..... overcut of 140% on 3.6mm material gives a final depth of 5.04mm, this is 6 passes at 1mm per pass with the last pass being 0.04mm deep, a waste of time, both in cutting and in generating the code!
if you set it to 138% overcut, then it will do 5 passes, with the first 4 beings. 1mm deep, and the last one 4.968mm.

other than that I cannot see any problems. take about 10 seconds to output Gcode on my i3 laptop.

 

PS: please consider upgrading to Sketchup 8 (the last Google version) or Sketchup Make 2015. 8 fixes many bugs in 7, and Make2015 has some really nice arc drawing tools, among other nice things.

 

how much RAM does the machine have?
I have found that loading an antivirus package will use up 2GB of RAM so if that is all you have the machine begins thrashing code pages to disk. Minimum usable RAM is 4GB but if you have 64bit Windows go directly to 8GB (as 2 x4GB sticks = faster access).

What may have happened is that an antivirus update has pushed it into code page thrashing, or installing some other package has used up just enough RAM to cause this issue. You see all those icons in the taskbar at bottom right? The more there are, the less RAM you have available. When this happens with our normal AV I uninstall it and install AVGfree instead as it has a much smaller footprint.