My computer is Dell XPS M1710 with 1 GB MB RAM
My Video card is NVIDIA GeForce Go 7900 GS 256 MB
I experience no abnormal lag and it looks as if I have less than the laptop you are looking at. But don't go by me. I'm not that familiar with hardware. In fact I wish I would have waited just a couple of months and I could have gotten a much better laptop from them. That's the problem with technology today. Improves too fast.
I am using v1.13 beta 4 and the fps rate is at 38 without characters for even large levels. The only time I see it go down is with a lot of characters but that is only down to around 28. This all depends on placement whether or not I use floorlogic, etc. So it really depends. With Lee's suggestion I can get a lot of characters close together and the rate is usually in the 30's and even around 37.
Hope this helps.
The past has a lot of memories to hold onto; but, today is chock full of new adventures, and, the future shouts out, "The best is yet to come!" -- TerryC