Clip an assembly to create a section for 2D drawing

[Jopie01]

I have an assembly with more then 100 parts created from straight beams to more complex extrusion profiles. Dimensions of the assembly are 8 x 2 x 2 meter. I have created a special DXF export system to create drawings from that assembly. To create the views I use HLRBRep_Algo which works very well.

However I want to create a section to show some internals. Currently I create a new Compound from the assembly, take the bounding box and create a larger box to cut about 90% of the assembly away. Then I can create a view which represents the section.

Some code:

side = cq.Workplane('XY').add(assy.toCompound())
bb = side.val().BoundingBox()

# based on the boundingbox create a set of points and draw a polyline and extrude
cutbox = (cq.Workplane('XY')
    .polyline(pts)
    .close()
    .extrude(bb.zlen + 10, both=True))

# create the cut
side_section = side.cut(cutbox.val())

# the side_section can now be used to represent a section view

But cutting takes a lot of time, it doubles the execution time. So I'm looking for something to use clipping in combination with the HRLBrep_Algo. Would this be even possible with OCC? Or do I need some other method?