i am just wondering if iOS 8 features (widgets ,spotlight, new keyboards and extensibility) could affect the iPhone 5s performance if they worked with multiple apps like what is happening in android these additions eat system memory and performance 
this picture from my iPhone 5s with no app running just system services (in idle time it shows 265MB free memory)
this picture from my iPhone 5s with no app running just system services (in idle time it shows 265MB free memory)