CPU speed stay at max for a while.

Any idea why this is happening.
I just installed avast free 2015 on my new pc and when I restart and check the task manager(I use Process Hacker)multiple times,I notest that around 1 minute after loading the desktop and instantly running the task manager(the os and avast are on my ssd),the cpu speed stays for a while at default speed(i7 4771 3.5Ghz)and after that goes below 770Mhz like usual.
The strange thing is that during that time nothing is running that could make the speedsptep feature to increase the clock speed(CPU,GPU,HDD,Network…all below 1% usage)

You may want to do a Forum search on NG.
Here is one thread: https://forum.avast.com/index.php?topic=157998.0

I didn’t install that because I don’t need it.
File and Web Shields are enough for me and as I said,there is not usage at all

The higher ram usage on the second picture is because I started 1gb ram drive after that