The FTB launcher isn't always recognized as a game for some reason.
Meaning the dedicated graphics card won't kick in since it doesn't know it's needed.
I've only seen this issue with nvidia cards so far, so i'm guessing that's what you have.
If so, go to the nvidia control panel, then find the "manage 3D Settings" menu.
On the global settings tab in that menu there should be a "preferred graphic processor" drop down box, probably set to "Auto-select".
Change that to "High performance NVIDIA processor" or something like that.
Hopefully that should make FTB run properly.
This will cause your computer to use more power when idling though.
So i'd turn it back again after playing if you tend to use your laptop while it's unplugged, but it doesn't do any harm to leave it on either except for reduced battery time. It should be possible to make the laptop treat FTB as a game by adding minecraft or the ftb launcher or possibly java in the "program settings" tab in the same menu.