i'm new at fpv and still learning. so what i think might not turn out to be true.

the feel and the speed is about the same as 3s or 4s ultra light 3". it's pretty slow. you should feel right at home.
3s X 5000kv = 15000kv whereas this build, 4s X 2000kv = 8000kv, so it's a 5in but the kv is very low, about half of 3in.

So you might think, why on earth would i build a 5in quad if it's that slow ? for one, i've built it because i'm curious. two, i've built it to test out a theory in my head.
it has the same speed as an ultra light 3" quad, but it somehow feels different. and i think it would make it easy for me to learn certain tricks. tricks that require air/hang time. once i've learned how to do those tricks i can go back and learn how to do them with smaller sizes like 3" quads or 2.5" or 2"

there's no way that your build is slower than my 3s 3" which is by no means slow. at 55ish degrees on the camera and full boogy im looking in excess of 80mph. my 1s build might hit 20mph with all the camera angle i can give it. i built a similar build with parts from a old Walkera rodeo that had more grunt and top end with the craptastic props that I had. it was fun but a tree jumped out at me and I couldn't dodge it in time. my main problem with a 5 in is a safe place to be able to fly and really give it hell

it's true. it has about the same speed as 3s 3". but if you want it to be faster you can use 5s or 6s.

it was 4s 850mah.