This article explains why there is a delay in opening a company the first time the software is started.
When you run the software for the first time after starting or re-starting your system, there is a delay. Closing and opening a different company or even closing and restarting the software does not cause further delays when opening companies. The reason for the delay the first time has to do with the database server software, Microsoft SQL Server. When accessing the server for the first time it needs time to make some server and database connections, establish memory usage, etc. Once this has been does it's available for further database server usage. If the server is never accessed or there has been a considerable period of inactivity the database server will release it's resources to the operating system.
This behavior is by design.