viewport shading

Hi guys, I noticed that in the viewport shading, bad work, quite often is not visible model.
And I want to ask accelerate programa, very lag's a hard scene, and with difficulty edit hard mesh , as well when dealing with boolean often falls programa.

Sory my english.
Thanks.

Still it would be nice if the object on which the cursor was illuminated
http://cs538108.vk.me/u43633640/docs/534079a4cdf6/Bezymyanny.gif?extra=dl7c7GC-7k9eZ2TOWagszXahXl3CPV2o1HyQPXNcga7F17U2DIxw9McAkmlqIadB-6fjmsm3azS8k69-XAgrko5cM4G0GrM

Ok, so even though I rarely understood a word you've written in your first post, your short clip delivered the message of the second post. It's selection highlighting in object mode. Not a bad idea!