iPad Pro RAM Usage

Hello, I want to ask.

iPad Pro has 4GB RAM, is it normal when RAM usage reach 2,7GB even without multitasking ? ( I didn't use any apps before)

I'm just realised that when I want to connect my iPad Pro to Wi-Fi. When I tap "settings" suddenly I've got some lag and delay almost 10 second to open settings.

If that's not normal like other iPad Pro, what should I do ?

Mine iPad Pro 128GB Wi-Fi Only model. iOS 9.1

Thank you.