Otherwise it doesn't reload everything. Verify this by watching the Developer Console's Network section. I can only assume this is intentional; my coworkers told me this trick last year and it still seems to be the case.
I still feel Chrome is the best browser, but that's more to do with the lousy competition than Chrome's own quality as of late.
About JS performance: Might be important to you as a gamedev, but for the overwhelming majority of today's web apps this shouldn't be an issue anymore.
That being said, I will probably still switch back to chrome when they get retina support. The interface is just cleaner and it has more intuitive developer tools IMO (safari's are more powerful, but chrome's do have everything I need and are easier to navigate).