Ino Detelić

Avoiding slow TRIM and EXTEND in DraftSight

In AutoCAD, EXTEND and TRIM are two of my most used commands and for I normally use them with the “select all” so I can keep extending an trimming without thinking what was selected or not.

This soon became a problem in DraftSight, as the TRIMs and EXTENDs were getting slower and slower to a point where it was no longer usable as the drawing was getting bigger, so I tried to find out why that was happening and I discovered that AutoCAD and DraftSight process the command differently.

Autodesk has some tricks that make these operations faster:

  • AutoCAD only takes into account the objects that are inside or near the display area;
  • AutoCAD doesn’t calculate trims for dimension objects.


DraftSight, on the other hand, computes all the objects, including dimensions in the drawing, not just the area you’re currently viewing. That’s why it TRIM and EXTEND on DraftSight is slow, especially with large drawings.


The solution, if you don’t want to select the objects for trim and extend, is to hide or lock the object heavy layers you won’t need for the trims and extends you’re doing, such as dimensions, vegetation, symbols and equipments and appliances.


Tip : you can use the LAYISO (layer isolate) command to select only the layers you need and LAYON (Turn on all hidden layers) or LAYERP (Previous layer status) to get back without having to go to the layers dropdown or manager.

(In reality I only use a custom TRIM with an enter to select all, and for EXTEND I press the shift key, so I never really use the EXTEND command)

Posted on December 13th, 2011 under CAD