18% is pretty decent, IMHO, for their bottom-most spec, especially given the RAM limit is being extended to 24GB, while the power consumption is still brutally good (18hrs video playback) and the screen is also a bit more spacious at 13.6"...
and it's not like they don't have faster CPUs. it's just the cheapest you can get and even that is getting faster!
tbh, im using an M1 Mac Mini since last December and it's sooo freaking fast and smooth, that I'm not even really motivated to upgrade at all, if it wouldn't be for the extra memory. though the 16GB is surprisingly sufficient too, if i have run browser tab suspender extensions and close my unused electron apps (notion, logseq, slack), while coding (in Clojure, using IntelliJ and Emacs).
They did not give any number for single-thread speed, so it can be expected that there the improvement is much less impressive.
They said that the little cores have been improved substantially, so it is likely that a good part of the 18% comes from the faster little cores.
1. 2017 3.1GHz Quad i7 clj -M -e 1 1.73s user 0.12s system 232% cpu 0.795 total
2. 2020 M1 Mac Mini clj -M -e 1 0.65s user 0.05s system 157% cpu 0.445 total
and I'm getting a very similar time-ratio, when I'm running our test suite for example. I find these speeds extremely satisfying already!