Dynamics AX 2012 R3 slower and slower

Hi,

I have one customer with Dynamics AX 2012 R3 (migrated from AX 2009), SQL Server 2014 Std Edition with 16 cores CPU and 96GB RAM, AX is running fine in 3 days then it goes slower and slower. Must restart SQL and AOS and then it runs fine in couple of days when new restart is needed.

AOS server have 4 cores CPU and 24GB of RAM.

I cannot find any performance issues with hardware, there to begin troubleshooting?

I´m technician so