The "machine-gun" sound of Spanish is more due to it being syllable timed, while English is stress timed.

https://en.m.wikipedia.org/wiki/Isochrony#Syllable_timing

Spanish also has heavy syllable merging, even across word boundaries. (Vowels merge together and hiatus turns into di- and triphthongs.) This reduces the number of actual syllables in speech.

https://en.m.wikipedia.org/wiki/Synalepha