The Amstrad CPC was one of the best 8 bit computer of his time in term of graphical capabilities. But this had a price...well, a weight in term of CPU ressources.
As so many games were ported from the "inferior" Spectrum, the Amstrad range could hardly benefit from his its main advantage.
As a result, so many games were slowler, painfully animated, with a bad gameplay...AND had badly ported graphics too.