Thanks for sharing the context @derrick 
The delay mostly sits in the product/variant creation step, which is a shared dependency for online store, POS, and anywhere else that needs the new data. I actually investigated this exact issue on the online store side recently in this thread, Intermittent 422 error when adding newly created variant to cart via /cart/add.js - #49 by jay_nl. As a result, we’ve made what optimizations we can at product/variant creation, but products and variants now have to handle a lot more than they used to, which limits how much we can optimize there.
I’ll forward this context along. It’ll help build a stronger case for the Cart Transform request.