Help me find a Productive Laptop

The issue that you are having with the Acer Aspire S3 is simply due to the lack of RAM. It only has 4GB of RAM and it cannot be upgraded. Based on what you are doing you actually need more than what is available. Because there is not enough RAM the ultrabook continually swaps data between RAM and the Pagefile. It is the back and forth read / write process which is causing lag in your ultrabook. The Core i5-2467m is actually more than capable of handling what you do because most of the time the laptop would more or less be idling if it had enough RAM.

1TB SSD are generally expensive, they generally cost $600 - $800. Here's one selling for $2,500 (OCZ 1TB SDD - OCT1-25SAT3-1T). I'm pretty sure that is due to the scarcity of that SSD. I have seen refurbished versions sell for $700. 1TB HHD are very inexpensive by comparison, ranging between about $100 - $250 depending on the model. However, prices could be different in China based on availability.

http://www.amazon.com/OCZ-Technology-2-5-Inch-Performance-OCT1-25SAT3-1T/dp/B006L7JM64

A SSD does not improve performance it only improves the responsiveness of the laptop when opening and closing files / booting and shutting down the laptop. A laptop with a SSD can generally boot up within 10 - 20 seconds vs 45 - 60 seconds for a HDD.

For what you do a Core i7 is not really necessary whether it's a dual core or quad core CPU. Unless you are doing financial modeling with Excel like Monte Carlo simulations or Morris Method, you do not really need a quad core CPU. Most people use Excel to manipulate some data for reporting purposes so a dual core CPU will be fine. The fact that you may have 10 -15 Excel and Word file open at the same time does not really have an affect on the CPU, that just means you are using more RAM.

For what you are doing, you will likely not see a performance difference between 3rd gen quad core i7 CPU and a 4th gen dual core i5 CPU. In general a quad core CPU can make a laptop / desktop feel a little more responsive if it is actively doing many different things at the same time. For example, if you are doing a virus scan, compressing / decompressing some file and watching a video you may notice some stutter / unresponsiveness with a dual core CPU versus a quad core CPU.

If you are looking at ultrabooks like the ThinkPad T440s, they all must use a ULV (ultra low voltage) CPU in order to qualify as an ultrabook because the CPU needs to be 17w TDP or less. Theses ULV CPUs usually have low clockspeeds and are all dual core CPUs. These are "U" model CPUs. While a light laptop is great, I personally prefer to stay away from them since I would prefer better performance in a laptop with a reasonable weight.

My next laptop will very likely be a quad core CPU since I do tend to do very CPU demanding tasks like video encoding from time to time. Depending on how the video is being encoded it can use up to 4 cores. And I also multitask a lot too so while I am encoding, I may also be surfing the internet doing research and also have Excel open. Or maybe play a game while a video is being encoded in the background.

I recommend that you consider laptops with 1600x900 or 1920x1080 resolution screens. The ability to actually multi-task is dependent on the amount of information you can see on the screen at one time. Higher resolution screen means you can have two Word documents or two Excel spreadsheets opened side by side. The more information you can see at a time means less time scrolling back and forth in large spreadsheets. I find the 1366x768 resolution screen on my Lenovo IdeaPad Y470 to be extremely limiting.

I was considering a ThinkPad T540p, but after reading / watching some reviews regarding the mediocre quality of the 1080p screen, the mediocrity of the chiclet keyboard (but better than a typical chiclet keyboard on other laptops) and the major complaints about the new mousepad, I am putting that on hold for now.

I much prefer the traditional style keyboard ThinkPads used to have. I find that my typing accuracy has decreased a lot when using chiclet style keyboards like on my Y470 laptop and I have been using it for over 2 years now.