Lasso line colour & AI slow-down after using lasso

How do I change the colour of the lasso tool selection line in AI? My artworks have black backgrounds so when I use lasso I can only see the selection line where it crosses other (non-black) objects which is rather annoying as I can't be sure what I have and haven't included in the selection.

Also why does it slow Illustrator down so much after using Lasso that I have to save, close and reopen AI to get the normal speeds of operation back?