The headword phrase comes from Aristophanes, Birds 1324 (web address 1). A similar gloss (θᾶττον: ταχύτερον ) appears in the Thomas Magister/Triclinius scholia to Clouds 1253. Though the Suda often contains entries deriving from the scholia to Aristophanes, this particular gloss is not contained in the old scholia to Birds.
cf. generally epsilon 108, epsilon 109.
[1] θᾶττον (headword phrase) and ταχύτερον (gloss) are both from ταχύς, ταχεῖα, ταχύ but while the former is good Attic, the latter appears in, e.g., Herodotus (see LSJ s.v. web address 2).