Hello AcerV3, thanks for joining the Intel Graphics community.
I’m afraid to tell you that this processor cannot be overclock since it is not an unlocked processor.
Regarding the performance of the game, it could be that Castlevania 5 is sending some command lines requesting additional features to the processor that POE (Path of Exile) is not doing.
I would recommend you to check if you can disable some advance feature from the game, and check if the performance increase. Also, if you have another system, please try to use the game on it in order to check if the behavior persisted, maybe one running Windows 7.
I found this forum from users experiencing the same behavior, please check it out. http://forum.paradoxplaza.com/forum/showthread.php?660514-Game-running-slow-Try-these...
In addition and since the other game is working smooth, I suggest you to contact the game developer for additional information.