MS SQL Expreess 2012 on SBO 9.2

Hello,

I work on SBO 9.2 with Sql Express 2012. The DB size is about 8 GB. The effectiveness of the application is horribly bad. Do you think the free version is the reason? I'm not the expert and my SBO supplier claims that the reason is rather not in the Express version. Nevertheless they don't know the reason, neither me.

Hardware:

MS Windows 2012 Server Foundation

SSD disks

16 GB RAM