pulse yoyo acting like loop 1080

General Yo-Yo
1

so recently bought some duncan pulse yoyos that came with polyetser string so when i throw them down they would sleep for 30 seconds nothing unusual.but when i put regular kitty string on them theyd sleep for for like 50 sec but with really really low response.just like the adjustable gap of loop 1080 i should know cause i have them.anybody know why they do this?btw im not a 2a pro so i dont know everysingle thing about 2a yoyo