iPhone 7 plus 10.3.1 issue

[_iOS]

I have recently bought a new iPhone 7 plus 32 GB, it was running 10.0.2 out of the box so I updated it to the latest 10.3.1. Recently i was comparing its performance to my iphone 7 running 10.1.1 the difference is very noticeable in graphics tests Such as Antutu and 3d Mark Slingshot Extreme. When I ran the Antutu test on both devices my iphone 7 plus was constantly stuttering and was very laggy throught the test however the smaller 7 went through just fine No lag at all. The score was also much higher on 7 (171k) and 7 plus scored just 145k. The performance of this 7 plus is also much lower in other tests such as 3D mark slingshot Extreme which scored 2100 I have youtubed some videos and somewhere in the comments a guy had similar issues on 10.3.1 he had mentioned that eversince 3.1 update graphics performance has reduced significantly. If any of you are running 10.3.1 can you please run Antutu test and confirm if they are also having too much lag during graphics test. I'd appreciate if you also post ur 3D mark slingshot extreme scores. I understand its nothing to be worried about because these tests dont relate to real world usage needs but still I am making sure if the GPU in my device is overheating or something.