It depends. You will have to run some performance monitors on your current box, to see if it is getting bogged down by a lack of CPU. If it is, then yes, the faster CPU could help. If you are more bogged down by disk access, you will see very little performance increase with the new CPUs.
For example, suppose a process takes 10ms of cpu time, and 100ms of disk I/O time. The whole process takes 110 ms. If you get a processor that runs twice as fast, you will end up with a process that runs in 105 ms. Just under a 5% increase in performance.
In general, if your CPU is staying up around 70 - 80%, I would go with the CPU upgrade. If it is consistently less than that, I would not bother.
Thank , I have peeks of ~ 20 minute each hour of ~ 80-100% CPU but , I am afraid that it is caused by the SQL server processing (lock management locks for example or other ) so any better CPU will not help ??