Performance on laptop

Recently got this game on GOG, it's great, really love it. I usually collect games like this to play on laptop while away from home. But there's something strange with this one, on my rig (Core i5, 8Gb RAM, GTX 560 OC 1Gb VRAM) I play it smoothly 60 FPS in all case scenarios, while on laptop (Core i3, 4Gb RAM, GT 820M 1Gb VRAM) in menu I get only 20 FPS, and in-game it goes to 30-40 FPS. Sometimes in combat it fluctates to 20 and so on. I made sure to check Nvidia Control Panel and it presumably works on 820M GPU instead of integrated one (I set each .exe on high performance GPU by default).

There are no graphic settings in this game to tweak, and it sure looks gorgeous, but that's hard to believe its graphics may require that much hardware power considering requirments... I play games like Darkest Dungeon, Door Kickers, Skyshine's Bedlam, and some more which are fit well for laptops and work smoothly on 60 FPS. It's not exactly gamebreaking to have low framerate in Battlestation, but I'm curious, is it normal or something could be done to improve performance?