I have purger everything saved with no plugin data and its still huge despite its a small model.
Run Audit3dm on the file (from another blank Rhino file) and post the results here… Possibly some ‘stuck’ large bitmap textures.
You probably have the advanced setting for mesh compression turned off.
Clearing out all render meshes and saving in wireframe mode results in 72MB file.
I suppose your custom render mesh settings add quite a bit of bloat.