QGIS and GRASS r.fill.dir processing times

I am new to the open source software and have performed analysis in ArcGIS in the past. I am learning as I go on this processes for OS. I am trying to calculate stream order (strahler) on a 1 gig DEM. I was able to do this very quickly (from fill through watershed) until I realized that my DEM imported into QGIS - GRASS plugin (mapset) without a spatial reference (i was never able to get to the strahler order portion to run). When I state the geographic (wgs84) projection and make sure the dem shows the projection, the processes take a really long time, I have been running the r.fill.dir for over three hours on this 1 gig file? Would projecting it to another CRS make it run faster? And would running in GRASS GUI or GRASS plugin/QGIS work faster? Am I missing something?

update: thanks to an answer here; http://ift.tt/1Ctywqt - I am trying this through the Processing Toolbar (QGIS)- & it works quick (tif,img) - with a zero output- unless I write the file to *.asc & I am now back to a long wait time....thoughts?

update2: I believe this has more to do with my processing CELL SIZE settings that I was not originally aware of - I have since figured out that when I bring data in QGIS & GRASS the default processing cell size is set to 500m - I was importing a 30m DEM - however since the processing area was set to 500m that is why it took so long..... sadness.. I am trying to find the fastest way to process hydrology information - which software would be the fastest option???