Dynamics Ax performance and SQL cores

Past few days i was at the customer site who was facing many performance issues in the Dynamics AX application . Many day to day operations were extremely slow and users were complaining a lot about the application performance. In my initial investigation i found the there were many configurations in SQL which were not optimized for Dynamics AX . Max degree of parallelism was not set to 1, only one tempdb data file was created and of course there were many indexes suggestions.  Other than these observations there was something unusual happening on the SQL server. SQL server had 8 cores but only 4 were utilized and were on the peak utilization most of the time.  I curiously looked into this direction and BINGO ! SQL server had only 4 processor license.
I used sp_readerrorlog to get these details. After updating the SQL license for 8 processors we got rid of  many performance issues.