When I import a drawing from a DXF or DWG file in to a SolidWorks drawing, the performance i get is very poor and slow.

The drawing has been exported from another CAD system but is purely 2D i.e. no 3D geometry involved.

Several blocks are contained within the drawing. Even if I explode all the blocks response time is poor.

If i try and stretch elements/lines SolidWorks seems to take a lifetime to compute the change.

Is this a known problem with SolidWorks or is there any hint or tips to speed up the performance whilst trying to move/stretch these lines.

screen cast to show the problem  http://screencast.com/t/qhcpe3JzCx8b

SolidWorks 2013 SP3