I am not aware of how many people have used the popsa app. For people who do not know about it this app allows you to select photos from your phones gallery, instagram, drives etc. and creates a photobook for you. Its an amazing app with a pretty UI and amazing UX. The thing I find fascinating about this app is how fast they upload the photos the users have selected. They also have a web app that synce the albums almost instantly from the mobile app. To do this the upload of the images has to be really fast.I have personally tested it so many times, created a photobook killed the app refreshed the web app and the album is there with all the images !! I tried building a very similar app with the same features the app is built using flutter. There is a screen that displays all the images the user has selected in a listView each widget in the list view is a page basically with options to crop the image, add a caption, change background color etc. I am having two problems which I really do not know how to solve yet I want to learn and grow.

I want the my apps main screen the screen where I am showing all the pages with the images to be smooth, sometimes if there are 100+ images selected it either gets slow or crashes (in a low - mid end device).I WANT TO OPTIMISE THIS. I want to achieve the fast upload that POPSA have right now I am optimising after the user actually places the order and then the user has to wait for the upload to get over. I want to do it faster and instantly as soon as the photobook is crated.