ZWCAD is cost-effective CAD design software based on IntelliCAD and developed by ITC member ZWSOFT. ZWCAD 2017 was recently reviewed by Jeffrey Heimgartner, an experienced CAD designer and manager at CapStone. The review highlights ZWCAD's speed of opening files, ease of use, compatibility, and performance.
It’s hard to beat the performance and features you get from ZWCAD 2017..." – Jeffrey Heimgartner
Here is a large 3D building model used to test stability and performance: