Shiny selectInput very slow on larger data (~15,000 entries) in browser

Question

I have this basic shiny app, and it is blazing fast in the \'Viewer\', but when I use the \'Open in Browser\' option, the select input choices take a while to load.

Answer 1

Hi try to put the choices in the server with updateSelectizeInput and use server = TRUE to store the choices server-side, e.g. :

library("shiny")
# mylist
selectList <- sapply(1:15000, function(x) paste0(x, "_", paste(sample(letters, 10), collapse = '')))
# ui
ui <- fluidPage(
  selectizeInput(
    inputId = 'mylist', label = 'Select Something',
    choices = NULL,
    selected = 1
  )
)
# server
server <- function(input, output, session) {
  updateSelectizeInput(session = session, inputId = 'mylist', choices = c(Choose = '', selectList), server = TRUE)
}
# app
shinyApp(ui = ui, server = server)

You have to use selectizeInput and not selectInput for this to work

Answer 2

I did it faster with data.table package:

library(data.table)
selectList <- as.data.table(sapply(1:15000, function(x) paste(sample(letters, 10), collapse = '')))
ui <- fluidPage(
  selectInput('mylist', 'Select Something',
              choices = c(Choose = '', selectList),
              selected = 1)
)

server <- function(input, output) {
}

shinyApp(ui = ui, server = server)