Using VCE on APU lower cpu frequencies?

So i've been trying to use vce on my igpu but when i used it the games fps drop, then i use cpu-z to track my cpu freq and it dropped to around 1.3-1.7 ghz

Is this normal?

 

Specs :  A8 6410 with R5 Graphics

              R5 M230

              8 GB Ram

              Windows 10 64bit

              Driver Version : 17.4.4