I'm running a Lenovo S540 (the line has been discontinued but it is an ultrabook). It's processor isn't as good as the 4th gen X1 carbon you can check the comparison here: https://www.cpubenchmark.net/compare.php?cmp%5B%5D=2608&cmp%...

My S540 has an SSD,16gb ram and the slower processor and it churns through work fine, I mainly do Java development and on top of that I use the Play Framework which compiles to both Java and Scala so it's more CPU intensive.

I can easily run one or two IDE instances alongside 10+ chrome tabs,several terminals and mongo/mysql db GUIs.