The thunderbolt Acasis enclosure seems to work well as boot drive with Ventura or Monterey, but it takes more than three minutes to boot under Sonoma. I also have spinning beachballs when I open some applications. I use a Samsung 980 Pro SSD, which was recommended by Acasis.
Mac Studio, macOS 13.6
Nothing wrong with that enclosure other than its high price.
I have three of these: https://www.amazon.com/Sabrent-Tool-free-Enclosure-Optimized-EC-UASP/dp/B00OJ3UJ2S/ref=zg_bs_g_23697346011_sccl_4/134-2227453-7199959?th=1
Just yesterday I created a bootable external drive for Sonoma on my Intel iMac using this PNY SSD: https://www.amazon.com/PNY-CS900-500GB-Internal-Solid/dp/B07XZLN9KM/ref=sr_1_3?crid=11NFMLSJAKCYU&keywords=PNY%2Bssd&qid=1697725361&s=electronics&sprefix=pny%2Bssd%2Celectronics%2C111&sr=1-3&th=1
It's connected via standard USB (USB-A) and boots just fine. A bit slow, takes maybe 30 seconds to get to the login screen, but after that it runs really well. Black magic app shows about 480-500 MBps read speed.
Since it was created to be part of a disaster recovery plan, it being a tad slow to boot is entirely acceptable.
I suggest you try a different SSD and/or a different enclosure.
I have read & write speeds of 2700 MB/sec with my Acasis thunderbolt enclosure. It works well with Ventura and Monterey, but not with Sonoma.
Slow boot on a Acasis TBU401E as bootdrive with a Samsung 980 Pro
