I got a large sketch and my computer has only 4 GB RAM and a i5 CPU. It takes about 15 minutes to open the sketch. Working in the sketch is impossible as Solidworks has is very slow then and crashes often.

Luckily I will need only a small area in the sketch for my work so I want to reduce the size to the necessary area.

How can I crop this small area in the sketch (like gimp scissors crop tool in gimp or similar photo editing programs)?

My idea is, to cut out the small region and save it again to a new, smaller file. The lines may be cut off, but should be fixed in their position.

The best would be to have the interesting area as fixed background in the new "working sketch".

Thank you for reading so far and thanks for any hints.