I have analysed the CPU usage of the Skype with the help of A+ Sytem monitor App. Here is the result.
I have checked the CPU Usage before starting the skype Application. It was showing 95.4% of CPU idles. And The CPU Usage is
CPU-System : 3.6%
CPU-User : 1.0%

After that I have checked the CPU usage immediately after starting the Skype Application and it was showing 81.1% CPU idle.
CPU-System : 12.2%
CPU-User : 6.6%

I was watching the CPU usage and it was increasing rapidly. After approximately 5-10 minutes the CPU idle reached 0% and 100% of CPU is used.
CPU-System : 69.5%
CPU-User : 30.5%

I have killed the Skype application and checked the CPU Usage again and it was showing 93.4% of CPU idles.
CPU-System : 2.5%
CPU-User : 4.1%

bdb31bfc-88c9-4090-a8ff-574679171eb8|2|5.0
English, iPhone
iPhone multitasking, Skype, iPhone