Not too familiar with mobile GPUs. Keeping that in mind...
The score your card gets in 3Dmark is 1060, which is less than half of a 7750. Based on that chart it should offer around a third of the performance of my 5770 which is 3 years old. Its very possible that the speed of your GPU is the limiting factor.
You can improve your performance by making sure your graphics drivers are up to date and that you have the latest CAP package installed. Also, lowering the settings in the game you are playing (highly recommended).
For slower cards you will see a big performance boost by dropping the resolution that the game is running at to the lowest you can stand to look at. Also disable things like AA / AF / V-sync altogether.
Things that your card is probably too slow to do or might only be able to run on low include shadows, ambient occlusion, and lighting / reflection effects. If you turn these things off / down you will see a noticable improvement in performance.
Personally, I like deskops because there is a lot more performance to be had at a lower price as you can see from the chart in that same link. You can always upgrade just one component if needed (I went from a 5770 to a 7870 earlier this month). If it fits your lifestyle I would consider getting a cheaper, more portable laptop for mobility and consider putting the cost difference into a desktop PC for tasks that need more power. A plenty capable gaming PC can be built for $600. I built mine for that price 3 years ago and I only upgraded the graphics card for the first time this month.