piezo latency , bad respond

Hi guys
I found this video - YouTube on how to make diy drum kit with arduino half a year ago and decided to do it myself. though i combined the idea with this project Homemade Electronic Drum Kit:Coltronics Kit-e - YouTube
despite all my efforts, drums dont seem to work effortlessly ... please help me if you find time.
there are several problems that i can't resolve.
first of all i have to set threshold to as minimum as to 2 or 3 or 5 to make pads react to the hit. which is strange itself. and also even at this threshold pads dont react to light hits which i would still like them to react to.
the second problem is latency or instability. because sometimes i do not notice latency but it may arise if i play Hihat and Snare and then quickly hit Crash cymbal. i mean there is delay when i do something abruptly , like arduino was not expecting it. and i also know that its not DAWs or program's fault because i see that its little light-indicator on arduino board is not in time.

here is how it works - YouTube
and photos https://www.dropbox.com/sc/a4hk3fsm7mk4wb3/AADEoB6a7IlbclXlA1jc3LKba

i bought chinese arduino and piezos on Aliexpress. i did everything on protoboard because i suck at soldering and would definitely mess the whole thing up. i followed the video of Evan Kale but i m not sure if its OK the way i connected everything on protoboard .

i use ableton and bfd2 .
i really dont know what is the problem. i guess its either piezos are not good or i connected smth wrong or i need to change smth in code.

Thanx!