Yep. The Amstrad CPC was an effective 3.3MHz. Most 8-bit machines of the early 80s had reasonably comparable CPU performance: the real speed differentiators were the graphics hardware (Spectrum fast because you had so few colour bytes to write, CPC slow - until you learned how to scroll with the CRTC) and, if you used it, the efficiency of the BASIC/firmware.

There was a 16MHz Z80: Amstrad briefly built a machine on it in the 1990s (the PcW16).