Shiny app file upload is substantially slower on different machines - r

Question

I have a shiny application that takes a file upload, calls a script that processes the uploaded file, and writes 4 csvs as output. The app works but as the title suggests, the file upload takes ~5 seconds on my end, but the intended end user is waiting 40 minutes for the same 32 MB file to upload. How do I reduce this upload time for them?
I am attaching my code, but here are some additional points that may be relevant:
The shiny code, the script it calls, and the file to be uploaded are all on a shared drive.
I am accessing their system through a virtual desktop, while the end user has a company computer.
Thanks in advance.
library(shiny)
source([removed for confidentiality])
# Define UI for dataset viewer app ----
ui <- fluidPage(
# App title ----
titlePanel("DFM File Conversion"),
# Sidebar layout with a input and output definitions ----
sidebarLayout(
# Sidebar panel for inputs ----
sidebarPanel(
# Input: Selector for choosing dataset ----
textInput(inputId = "exportname1",
label = "Credit Detail [003 Record] Output Name",
value = ""),
textInput(inputId = "exportname2",
label = "Location Bank Deposit [013 Record] Output Name",
value = ""),
textInput(inputId = "exportname3",
label = "Batch Summary [025 Record] Output Name",
value = ""),
textInput(inputId = "exportname4",
label = "Rejected Transactions [029 Record] Output Name",
value = ""),
fileInput("file1", "Please upload a file")
),
# Main panel for displaying outputs ----
mainPanel(
verbatimTextOutput("summary") #shows what files were converted
,h3(textOutput("caption"))
,tableOutput("view") # shows which records are not present in uploaded file
,h3(textOutput("caption2"))
,tableOutput("headdf") #shows first 5 rows of uploaded file
)
)
)
server <- function(input, output) {
options(shiny.maxRequestSize=60*1024^2)
# This reads in the uploaded file from the UI and outputs the first 5 rows
# Then it uses the export name entered by the user to convert the file
# using the conversion script.
output$view <- renderTable({
req(input$file1)
df <- read.delim(input$file1$datapath,header = FALSE, stringsAsFactors = FALSE)
converted <- convertdfm(df, input$exportname1, input$exportname2, input$exportname3, input$exportname4)
# this populates which records are not present in uploaded data
return(converted$output)
})
# this prints the first 4 rows of the file
output$headdf <- renderTable({
req(input$file1)
df1 <- read.delim(input$file1$datapath,header = FALSE, stringsAsFactors = FALSE)
head(df1)})
# this creates the first caption
output$caption <- renderText({
req(input$file1)
print("Checking Input Files for Unavailable Records")
})
# this creates the second caption
output$caption2 <- renderText({
req(input$file1)
print("First 5 Rows of Raw Data")
})
# this shows what files were converted
output$summary <- renderPrint({
req(input$file1)
if (file.exists(input$exportname1))
{print("003 Converted")} else
{print("003 Not Converted")}
if (file.exists(input$exportname2))
{print("013 Converted")} else
{print("013 Not Converted")}
if (file.exists(input$exportname3))
{print("025 Converted")} else
{print("025 Not Converted")}
if (file.exists(input$exportname4))
{print("029 Converted")} else
{print("029 Not Converted")}
}
)
}
# Create Shiny app ----
shinyApp(ui = ui, server = server)