I have a laptop, DELL Inspiron 17R with:
Intel Core i7 3537U of 2.00 GHz (3.00 GHz with turbo boost)
AMD Radeon HD 8730M
8GB of DDR3 RAM
1 TB of hard drive
I have many games. I have Minecraft, Black Ops 2, and others. I've had this laptop for a year. I've never had lag in any game. Minecraft runs at 60-70 fps with the highest graphics settings. Black Ops 2 runs at 40-50 fps in medium-high graphics.
About 2 days ago Minecraft started lagging. It decreased to 40-50 fps. Black Ops 2 lags for like 10 seconds running at 10-20 fps, then it goes back normal. I checked and I have my laptop running at High Performance. All the AMD Drivers are up to date.