The first thing this shiny app does is load a large spatial database of trees. This takes a few seconds.
Is there a way to always have this data preloaded to minimize this delay.
App can be found here:
https://lawrencepilch.com/tree/
For quick loading of large databases, I've found the storing and reading the data in feather format (feather package) is faster than other options in shinyapps.io. The feather files are fairly large, however.
Yes, feather is fast. Unfortunately, I don't think it works with spatial databases. I got a decent speed increase using a .Rda file rather than the db itself.
You could try storing as a feather that also has columns for x and y in WGS84.
I feel like this is too obvious and it can't work for you but why don't you just do it in global.R? Then it will be preloaded for each visitor.
If you need to update the data (by restarting the application) at intervals you can do that. See here http://docs.rstudio.com/shiny-server/#schedulers-application-restarts