I have some problem with the speed rhino works for me. This is what I do: I create a small cube, I array the cube in a three-dimensional rectangular shape, I apply ‘pipe’ to have a circular cross section of the cube beams, then I apply the ‘boolean union’ to unify all the extrusions. My problem is that ‘boolean union’ works very very slow for my geometry.

Could anyone suggest a alternative method to create such geometry, and works faster?

Boolean union of several polysurface will, I think, test each pair for intersections.
It should be immensely faster to pipe and boolean union one cube and then do the array.

If part of the pipes are “shared” by neighbour cubes, you should take the time to trim the common parts before arraying and then use Join.

Thanks for your reply. Fo this cubic shape, each cube in the borders has 3 ‘shared’ borders with neighbors, and each cube in the middle has 4 ‘shared’ borders with the neighbors. You mean I apply the ‘trim’ manually on each shared border?

Hi Mary - make one unit, that has all the trims in place for the interior objects and array it. Then you can modify the four corner pieces by hand, untrimming the appropriate faces and retrimming as needed,