I’m trying to make my Ionic 4 app appear more fluid, and whenever I navigate to a new page the app shows a white screen until the new page is completely loaded and ready.
Is there a way to remain on the current page until the new page is loaded and ready, then immediately display the new page, without the awkward white screen flashing between the two?
There isn’t a way to “wait until loaded”, as far as I know, but there is a way to “preload next page(s)”
If you want to only preload one or some particular pages, have a look to the article I wrote about the solution we found with @AaronSterling 
https://medium.com/@david.dalbusco/preloading-modules-in-ionic-v4-1839c34384fb
If you rather like to preload everything, Angular offers a preloading strategy which could be added to app.module (which btw. I never tried yet) https://angular.io/api/router/PreloadingStrategy
P.S.: Link to the related topic on the forum V4 preloadModules?