Hi,
gave up in V8, save as V5, open the v5 then click save and wait 19 secs.
open the V8 file and 1 sec save.
why ?
Its a mesh and just a few dims and curves.
Unable to use V8 with vanishing control points. so use V5.
but its horrendously slow.
What is your OS? note that Rhino 5 is not supported in Windows 11 anymore (Rhino 5 was last updated in 2017). We can speculate a bit on the cause if you post the file. Thanks!!