The X270 has a 6th or 7th gen dual core CPU. If you get an 11th gen i5 like you'll find in the sub-$1000 laptop range you'll get something that is literally twice as fast as even the highest end 7th gen i7. That is a lot of performance to leave on the table.
you'll find in the sub-$1000 laptop range you'll get something that is literally twice as fast
That's true, but it would require some combination of major compromises on the SSD, RAM, hot swappable battery, build quality, form factor, and keyboard/trackpoint. I'm almost never CPU limited in my day to day workflows, even on a 2nd gen i5, and I have cloud resources available when I need to do something CPU intensive like model training for work. It's a tradeoff that isn't right for everyone, but those other factors are far more important to me than the CPU.
X220 is my primary computer. It never uses more than 4 of the 16GB RAM. I ran the fan almost all the time at full speed tough.
The killer app (in a bad sense) is Zoom. It kills the CPU and can't handle virtual backgrounds.
