Despite the slimmer lines, Nokia keeps the internal specifications largely the same, so you're getting an identical dual-core 1.5GHz processor and 1GB of RAM, although this time there's only 16GB of storage -- sacrifices had to be made somewhere, we guess.
Performance, in general, was identical to what we've experienced on both the 928 and 920 (the same processor will do that), keeping up with our task transitions and web-browsing tests.