There are many performance enhancements in SQL Server 2014.

1. Standard and BI Editions now support 128 GB of memory (SQL Server 2008 R2 and 2012 only supports 64 GB).
2. In-Memory Online Transaction Processing(OLTP)  a new in-memory engine is a new lock-free, latch-free, optimistic concurrency approach to storing your data in memory. This is nothing like DBCC PINTABLE we might remember from years ago, which still suffered from the locking and latching problems that are resolved in SQL Server 2014.
3. SQL Server 2014 now supports native backup encryption in Standard, BI and Enterprise Editions.
4. Support for window functions, which makes it possible to write fast queries for running totals, sliding windows etc.
5. Columnstore indexes, which can speed up data warehouse enormously. But of no interest for OLTP. Only writable in SQL 2014.