It’s a myth that capricorn tubing is better in any way
I’d call it “successful marketing” :) But yeah, they’re really managed to convince a lot of people that it has near magical properties, and I’ve seen a lot of random people recommend it to others for all sorts of issues.
Did you follow some guide when replacing the nozzle and bowden tube? Did you hot tighten it when putting them back?
What speed are you printing at, which you think is too slow? What’s your acceleration?