When importing DXF/DWG data, tracing sketch pictures, or importing ECAD circuit board routes into a part or a drawing you may find yourself working with a overly complex sketch.
To improve the import processing time of these files you should pay close attention to the import options and clear the “Add Constraints” check box. This will prevent SolidWorks from adding relations to the sketch entities such as horzontal, vertical, concentric and so on.

If you attempt to move any of the entities in the sketch after importing the file, a warning message pops up that indicates ‘Automatic Solve Mode’ is off. This Specifies whether SolidWorks should automatically do the computation to solve the sketch geometry of your part as you create it.

In order to make this sketch more manageable you can use the ‘Make Block’ command to combine sketch entities together into a group. This prevents SolidWorks from calculating the sketch entities and their relations.

In this example over 4500 sketch entities can be reduced to 1 block by using the ‘Make Block’ command found under the Tools > Blocks pull down menu. Once you have created your block(s) to simplify your sketch you can turn Automatic Solve back on from the Tools > Sketch Settings pull down menu. Creating blocks in a sketch is similar to breaking a large assembly into multiple subassemblies in terms of performance.