Express editions are limited, see Features Supported by the Editions of SQL Server:
- Maximum Compute Capacity Used by a Single Instance: Limited to lesser of 1 Socket or 4 cores
- Maximum memory utilized: 1 GB
- Maximum relational Database size: 10GB
These limitations apply to 2008R2, 2012 and 2014 versions, and for 2005 and 2008 the max database size is even less: 4GB (CPU and memory restrictions are the same).
To troubleshoot your performance problems I recommend you read How to analyse SQL Server performance. If you discover that (likely) you are hitting the Express Edition limitations then you need to upgrade to a paid license edition (probably Standard). You will know you are hitting the limitations:
- if you see CPU contention you'll see high
SOS_SCHEDULER_YIELD wait times and high CPU perf counters on only 4 cores while otehr are idle.
- symptoms of the 1GB memory utilization you'll see high
PAGEIOLATCH_XX wait times and high disk utilization on OS counters (low memory triggers more IO).
Upgrading Express Edition from 2008R2 to 2012 should be a trivial matter, same for 2014. I don't think there is any feature in 2014 or 2012 that you could leverage in Express Edition, but reasons to choose the latest version always exists: T-SQL language enhancements, product support. See What's new in SQL Server 2014 and What's new in SQL Server 2012.
Microsoft has recently revealed (without a lot of fanfare) that they will be investing in TLS 1.2 and phasing out SSL. It should be relevant to all editions of SQL Server.
UPDATE 2016-01-29 : Microsoft has announced official support for TLS 1.2 in 2008, 2008 R2, 2012, & 2014. Downloads and other info can be found in KB #3135244.
I blogged about a few of the issues that have been mentioned, as well as a warning if you are using encrypted endpoints in 2014:
The post also points to the correct build to download (or other action) depending on @@version.
Whether this move will affect all existing versions, just 2014 and above, or just 2016, remains to be seen. The quote below seems to imply at least 2014 will be part of the work - and I suspect much of the investment will be in the client libraries, not in the engine, so it is feasible that it will work for any version that the next release of the ODBC/Native Client drivers will support.
I got this from a PowerPoint deck by Kevin Farlee of Microsoft, and was given permission to share the information, though I don't know how much of it has been redistributed at this point. Here is the exact quote from the deck:
Encryption in flight: Protects data between client and server against snooping & man-in-the-middle attacks. Upgrading to TLS 1.2 in CY 15, phasing out SSL.
Also if you look at KB #3052404, it seems there are patches to make it work with 2012 SP+ and 2014 (patches won't be required for 2016), but no indication there will be any back-porting to SQL Server 2005, 2008, or 2008 R2 (and frankly, I'd be quite surprised).
Best Answer
There would not be any noticeable performance benefit if you move to higher version of windows server. Normally people move to higher version keeping support in perspective and the host of new features they get in newer version of windows. Refer Compare features in Windows Server versions to see list of new features you get in various versions of Windows Server.