I'm afraid I'll have to disagree with Indy on his point 2:
2.Upgrade to 64bit SQL2012 Express
We can help you do this, and there are no licensing costs, just labor time to do the upgrade. This will allow SQL to access far more of that memory you already ahve.
SQL Server Express 2012 uses only 1G of memory regardless of whether it is 32 bit or 64 bit.
Please note that maximum database size goes up to 10G from previous versions so practices that are filling up SQL Server 2005 Express have at least one reprieve when upgrading.
https://msdn.microsoft.com/en-us/library/cc645993(v=SQL.110).aspx
JamesNT