When I play Minecraft, the game is lagging terribly however when playing other games such as Starcraft 2, Portal 2, Leaue of Legends and Team Fortress 2 it works fine. Only the Minecraft is lagging. Video settings for Minecraft has been set to its lowest.
Issue is being caused by the software not using the discrete card in order to run the game. Thus you would need to manually select the Nvidia GPU to run the game instead.
Right Click on Minecraft -> Run with graphics processor -> High-perfromance Nvidia Processor
*Screenshot below is for example only*
Another alternative is to use Nvidia Control Panel by adding the Minecraft then selecting "High-performance NVIDIA processor".