Solved by Shisho_Sama in post #2 
              
              
                OK, it seems like a bug in 1.6 only as upgrading to 1.7 fixed this issue! 
here are the results in 1.7: 
Graph mode static quantization : 
Quantization is done!
Default Model:  took 895.521 ms [min/max: 895.5/895.5] ms
Quantized Model:  took 337.002 ms [min/max: 337.0/337.0] ms
default model size: 2…