I resized my droplet from 512M/1CPU to 16G/8CPU. About 10 hours ago, I run a program that requires large amount of computing, the 8CPUs worked well.

However, when I run another program that also requires large amount of computing, it took the program hours to run while the Graphs shows that only 12.5% of CPU was used.

I checked CPU status by using htop command, it shows that usage of 4th core was 100%, the usage of other 7 cores varies between 0.0% to 1.3%.

http://imgh.us/htopinfo.png
http://imgh.us/Graphs_cpu.png

Is there anyone can help on this problem?