There's nothing better than installing 16GB of RAM in your Lenovo Thinkpad. This tutorial shows you how to safely upgrade your Thinkpad memory in less than 3 minutes. See for yourself how super easy and worthwhile this upgrade is.
CORSAIR Vengeance 16GB (2 x 8G) 204-Pin DDR3 SO-DIMM DDR3 1600 (PC3 12800)
Model #CMSX16GX3M2A1600C10 - http://amzn.to/1DFKFsc
I highly recommend you upgrade your Thinkpad to the 16GB max - it's an entirely different laptop - crazy fast. With RAM prices so cheap now, you would be silly not to do this upgrade, seriously. This specific RAM is less than $200 and usually on sale for about $120. Again, this is just one of those upgrades where your increased time benefit far outweighs the cost - no more lag.
For those of you that did this upgrade, feel free to comment below with how much you love the performance increase.