AntiXSS in Asp.Net 4.5

Hello,
1. I have not used HTMLEncode till now in my applicaiton. If I use AntiXSS in 4.5, should I write HTMLEncode for every control on every page to prevent XSS attack ? If yes, Is there any way it prevents automatically without setting encode on every control on every page.
2. How is the performance if I use AntiXSS in Asp.Net 4.5 ?
Thanking you in advance.
Best Regards,
Kiran