I think i found something quite interesting regarding the problem of the CPU usage, it is nothing to do with enabling and disabling the Video during the call, but it is related to the time duration of the Video Call,
If you look at my "Screen" sequences, you can see that after about 11 seconds since the Video Call starts the RPRVT memory usage is at 99M+ (first Screen)
then after 22 seconds it is 142M+ (second Screen) after 1 minute is 305M+ (third screen) and After 1 minute and 22 Seconds it goes over 350M+, (fourth screen)
After this value the CPU jump to 120% and more and never go back also after the call is closed the RPRVT stay at 360M+ and continue to growth again, so a reboot is needed.
There shoud be something that growth the usage of the resident private memory