Slow AX 2009 infrastructure

Hi everybody,

we have implemented a small AX 2009 infrastructure in early 2012. There are 5 servers running Windows 2008 R2 in a virtual environment, each one with a specific role as per Microsoft recommendations.

Enterprise portal: 2vCPU 4GB RAM
File server 2 vCPU 4GB RAM
Terminal server 2 vCPU 4GB RAM
SQL Server 2vCPU 10GB RAM

We have maximum 30 concurrent connections through a Remoteapp session (and max 10 connections through EP).

User sessions (in TS) are often slow, with delays and blank screens. Printing experiencing is slightly better but not very very fast. Users would like a more responsive environment.

What can we do to improve performance?

Thanks for any suggestion.