If performance issues cannot be resolved，I have to give up shapr3d

[Istvan]

Here it is:

Is merging history supposed to increase the file size?

No, it does not matter. I’ll now try to go into the technical details of how a CAD system works to explain why it doesn’t matter, but it’s a bit beyond the scope of this forum. As a start, I recommend reading this article: The technological foundations of CAD software In a parametric CAD system, under the hood what you need to store is a sequence of the operations, that looks something like this: sketch (list of lines arcs constraints etc) extrude (references to the sketch) fillet (referenc…