I'm a developer and bought the T550 for a job i did.
It has a two core CPU, but i was mislead by the i7 5th Generation hype.
You will find no review on Youtube on elsewhere claiming that it is desk top replacement. The reviews i have seen, will not even mention it's performance in relation to the McBook Pro or the Dell XPS 15.
Why did i buy it? The Hype. Lenovo Claims it is a high-end "Business Laptop". Desktop replacement? -- well i guess i've been duped.
I should have bought the XPS 15 which similiar to the Macbook Pro 15 has a 4 core i7-4712HQ (MBP has a similiar 4 core CPU I7-4870HQ)
The CPU is an i7 "4th Generation" CPU, but it is (in my opinion) faster than the 2-core i7-XXXXU "5th Generation" CPUs, sported by the T550. I am writing this because i had colleagues with the DELL MX4800 & DELL MX3800 laptops in the office, sporting similiar "4th Generation" 4-core CPUs (their machines were purchased in 2013 & 2014) Their compile times where at least twice as fast. And my T550 had serious problems dealing with extra monitors. The T550 has an i7-5600U CPU. These CPUs (i think he U stands for "Ultra" low energy), it use less energy and allows the user more battery life.
But if they do not perform, it like driving a 5th generation Vespa because you get more gas mileage and it is quieter, than on a 4th generation BMW motorcycle.
As a developer my laptop needs CPU muscle and no heat on top, allowing the wrists to remain near the keyboard the entire day. If the fan makes a bit of noise or if i have to plug it in every 3-4 hours, it is more than worth the compromise.
Even as i write the this review, my Internet Explorer has about 15 Tabs open and i have two sessions of Visual Studio running, skype, a couple PDFs open, Word is Open. And the mouse freezes on me. It is slow.
My MBP is also opened on my desk -- similiar load. It has no Problem. It makes some fan noise sometimes. So what. Better that it freezing up on me because of the load.