Well, in my experience Safari is slower in performance with all the mentioned stuff (gradients, fixed elements etc.) and more importantly slower with some fairly trivial stuff like CSS opacity or background transitions (and if you place some layers on top of one another for some hover or touch effects it can become really crippling for browser). I've yet to see real world example where Safari outperforms Chrome.
Well, in my experience Safari is slower in performance with all the mentioned stuff (gradients, fixed elements etc.) and more importantly slower with some fairly trivial stuff like CSS opacity or background transitions (and if you place some layers on top of one another for some hover or touch effects it can become really crippling for browser). I've yet to see real world example where Safari outperforms Chrome.