Hi!.
Slow performance can be lack of configuration in Database, SAP Performance Parameters, or Operating System configuration.
For Database you should check the respective note for your Oracle 12 -
1888485 - Database Parameter for 12.1.0.2
618868 - FAQ: Oracle performance
1171650 - Automated Oracle DB parameter check
For Operating System performance -
I think you have a typing error on paging in C drive, 20480-3000MB , 30000 MB right ? Either way please check the following notes:
1614339 - Page out rates on Windows Server 2008 (R2)
1246467 - Hyper-V Configuration Guidelines
1409608 - Virtualization on Windows
And please check the RSECNOTE and RTCCTOOL report's in SE38 for hints about slow performance.
Good luck!