Numerous licensing changes were introduced in SQL Server 2012; the most significant was the move from socket-based licensing to core-based licensing for Enterprise Edition. One of the challenges that Microsoft faced with this change was providing a migration path for customers that previously used Server+CAL based licensing for Enterprise Edition prior to SQL Server 2012. Customers under Software Assurance can upgrade to SQL Server 2012 Enterprise Edition and still use Server+CAL licensing (also known as "grandfathering") but with a limitation to 20 logical processors, as documented in the SQL Server 2012 Licensing Guide.
During some restore operations in SQL Server, the transaction log redo step might be taking an unusually long time. Depending somewhat on the version and edition of SQL Server you've installed, you may be able to increase performance by tinkering with the readahead performance for the redo operations. To do this, you should use the MAXTRANSFERSIZE parameter of the RESTORE statement. For example, if you set MAXTRANSFERSIZE = 1048576, it'll use 1MB buffers.
The quality of an execution plan is highly dependent on the accuracy of the estimated number of rows output by each plan operator. If the estimated number of rows is significantly skewed from the actual number of rows, this can have a significant impact on the quality of a query's execution plan. Poor plan quality can be responsible for excessive I/O, inflated CPU, memory pressure, decreased throughput and reduced overall concurrency.
As you have most certainly heard elsewhere, SQL Server 2012 finally offers a version of Extended Events that is a viable alternative to SQL Trace, in terms of both better performance and event parity. There are other enhancements such as a usable UI in Management Studio – previously your only hope for this was Jonathan Kehayias' Extended Events Manager.
I have a few people to thank for a recent update to Plan Explorer. Brooke Philpott (@Macromullet) and Greg Gonzalez (blog | @SQLsensei), of course, for R & D and for digging into the code and sorting it out. But also to Paul White for being persistent in helping us validate the fixes.