[Q] Performance Issues topic

I purchased a new prepaid T-Mobile Note 4 from BestBuy few days ago. Today I have noticed that when I run benchmarks, I am getting very low scores. On Antutu, I am only getting around 26000, but sometimes I am getting the normal scores i.e, 46k. Even when running other benchmark applications, I noticed that I was getting only around half scores but sometimes I am getting normal scores.

I don't understand this strange behaviour. Is my phone defective ? Should I return it ?

P.S: I have not rooted this phone. I tried a factory reset, and there is no power saving mode turned on.