New 3ds loads considerably faster than og 3ds. Using mine and Kobral's current all ocde cubes pb, I times some of the stages. My final esitmate is ~7minutes saved for any%, ~8.5 for all code cubes and 15-20 for 100% (depends on sticker rng). If you want to tiem the rest of the stages so we can compare them more accurately for whatever reason, then make a copy of this spreadsheet and time the rest or feel free to time every single stage yourself. 

https://docs.google.com/spreadsheets/d/1kPrMlqNZWYGC4r6x9pvh1DqxzJzgbIEZSFOACRvTzgI/edit?usp=sharing

Notes:
I used rowvid for the timings
The vid for my run is only ~15 fps so it may not be very accurate. For the most accurate result you'd have to do a full run on both recording at 60fps on both
Lag is a timeloss for og 3ds runners but I odubt it loses more than 10 seconds
I know this post is very late but nothing I can do about that

Important to note this doesn't impact times for Meta Knightmare Ultra due to ingame timing being consistent for 3DS and New 3DS.

My Any% record is 1:42:59 on New3DS and 1:49:47 on 3DS.
So My estimate is 6:40 ~ 7:00 for Any%.

New 3DS VS OG 3DS

Theguesst

Woutt64

Sidarino

yosshiV3

Kirby: Planet Robobot

New Nintendo 3DS

nicefighter

USA / NTSC

Kirby

$200 bounty on a KPR and KTD autoscroller speedup glitch.

3D rumble or Kirby clash

Change to MKR Rules

Regional Differences with the Hammer Ability?

I found kurohito’s Meta Knightmare Returns run

Level 1-2 skip

Kobral

swordsmankirby

shirokirby

Demolition14

Ezradekezra

sokuno

Revv

Kaiphenix

Craft102