After SGOS 6.7.x and later versions, when navigating under CPU monitor advanced url https://<Proxy_Host>:8082/Diagnostics/CPU_Monitor/Statistics , it shows CPU 0, and the other lower CPU cores always running higher than the later (higher-numbered) cores.

This is expected behavior.

In SGOS 6.7.x and 7.x CPU utilization of all cores are not evenly balanced across all cores, compared to 6.6.x and older SGOS versions- where the last set core(s) were always reserved for TCP/IP (on devices that had 4 or more cores). With the new CPU task distribution algorithm implemented in SGOS 6.7.x and 7.x application, the processing is distributed across all processes (no reserved core for TCP/IP). With this new task distribution algorithm, you may observe that CPU 0, and the other earlier CPU cores always have higher utilization compared to other cores.

It is normal for CPU0  (and then CPU1, CPU2, etc) to be loaded higher than the remaining higher-numbered CPUs on muti-core SG/ASG/SVGA devices. This is due to the newer algorithm used for scheduling works/tasks prefers a lower number of cores for coreOS/networking-related tasks until it becomes busy, and then starts to use the remaining CPU cores. Essentially, if CPU0 and the other earlier CPU cores have available cycles, they will continue to have preferential scheduling causing them to appear to "spike".

However, since CPU0 and the earlier CPU cores are NOT CPU bound there is no impact on end-user performance. As CPU0 and the earlier CPU cores continue to increase, some load will fall over to CPU1, then CPU2, CPU3, etc. So you will essentially see a distribution of CPU load, weighted higher for the lower number CPU numbers. But as load increases, it will essentially be evenly distributed when the SG/ASG/SVGA is placed high workload environment or when traffic volume increases. 

See the referenced CPU statistics attached.

Limitation: For SGOS 6.7.5.x the number of CPU cores should not be more than 24 cores. This limitation is handled in the 7.3.x and more than 24 Cores can be used.