This is My System
Lenovo Z51_70
Processor Intel(R) Core(TM) i7-5500U CPU @ 2.40GHz
Video Card 1 AMD Radeon(TM) R9 M375
Dedicated Memory 4096 MB
Total Memory 4.0 GB
Video Card 2 Intel(R) HD Graphics 5500
Dedicated Memory 128.0 MB
Total Memory 4.0 GB
Memory 16 GB
OS Windows 10 64bit
The HD 5500 running on since it uses that instead of R9 M375.HD is the integrated graphics, they are terrible compared to your card, try disabling it in the BIOS ( there will be a option called Onboard/integrated graphics. After disabling then save it and exit ), if that does not work disable it in device manager on Windows, it seems that you are using HD instead of the card and thats why you are getting poor performance.
also, since on laptop, obviously make sure on your "Power Options" you are in "High Performance" (Control Panel\All Control Panel Items\Power Options)
Well my first thought is a virus have you done an antivirus check on it, Avast has a free trial of Avast internet security, just look carefully under the cost and click on the trial button https://www.avast.com/...t-security, you could use Advance System Care, but I advice you run system restore first as a beginner you may delete things you don't want to by mistake, press windows key and r> type rstrui, read carefully and follow the prompts. This is Advanced System Care link http://advanced-systemcare.software.informer.com/download/