Alas, my favorite benchmark site has a limited selection of mobile CPUs but look here: http://cpu.userbenchmark.com/Compare.../m4821vsm12071 http://cpu.userbenchmark.com/Compare...m13661vsm12071 the effective difference is 21% and 33% -- exactly as their clock speed would suggest (21% and 36%). So a Celeron 2980U @ 1.6 GHz would be negligibly slower than the i3-4010U @ 1.7 GHz. They are both Haswell cores and the few additional features of the i3 series simply do not translate into real world wins.

Let's do another comparison: http://cpu.userbenchmark.com/Compare.../m4821vsm13386 this time the effective speed difference is 60% because the N2930 is a Bay Trail core.

Let me emphasize again: core technologies matter way, way more than "Pentium", "Celeron" and such labels.