How to fetch and create dataframe faster in R

Question

I'm using following query in R, the Query Run time is < 50 sec to fetch millions of records however while converting the output into dataframe using dbGetQuery it takes almost an hour. Please suggest how can I optimize the dataframe creation process in R.

Please help me with a faster approach to fetch query output in R dataframe.

# Define your start_date as needed
custom_start_date <- "YYYY-MM-DD"  # Replace with your desired start date

# Construct the SQL query with generic variable names
custom_sql_query <- sprintf("
WITH FirstInstance AS (
  SELECT var1, 
         MIN(var2)
  FROM delta.var3.var4
  WHERE date(var2) >= date('%s')
  GROUP BY var1
)
SELECT var1, 
       var5,
       var6,
       var7,
       var8,
       var9,
       var10,
       var11
FROM delta.var3.var4
INNER JOIN FirstInstance 
ON var1 = var1
AND var2 = var2", custom_start_date)
# Fetch the data
df <- dbGetQuery(con, sql_query)