Benaston, not only poor performance; I found out that with a certain number of 2D drawings ( >50 or so) Shapr3D will crash every now and then. I have the same issue with deletion; I have large number of 2D drawings and it is undoable to delete. It should be fairly easy for Shapr3D to solve by adding swipe to delete instead of select - delete - confirm.
We actually fixed an issue recently related the this. If you update to the newest release (5.410) and still experience poor performance or crashes when having more than 50 drawings please let me know and if possible send us the affected workspace with opening a support ticket here and we will be happy to investigate.
The solution is to export as a X_T file and then re-import from that file into a new drawing. X_T is a native Siemens Parasolid drawing and will immediately eliminate all drawings.