Slow monterey boot in my external ssd using macbook air 2018

Hi,

i have MacBooK Air 2018 128GB

the mac have no enough storage so i bought san disk external storage SSD 1TB and download the MacOs before monterey and was working great then i upgraded to monterey and now i have slow booting problem

when i press on button the apple logo and the downloading bar take 15 minutes till complete and the mac function!!

it's been a while and i have't find a solution, any one can help?