New features in .NET 4.5

• Async and wait 
• Zip Compression
• Regex timeout
• Improvised garbage collector
• Profile optimization (Improved startup performance)
• Set default culture to App Domain  (helpful in working on multi threaded environment)
• Array support more than two gigabyte size
• Asynchronous HTTP Modules and Handlers.
• New Request Validation features in Asp.Net 4.5