I have loads of .csv files I need to convert to .xslx after applying some formatting.
A file containing approx 20 000 rows and 7 columns takes 12 minutes to convert.
My suggestion here is to read the file by yourself and then use the library to create the file.
The code to read the CSV could be as simple as:
List lines = new List();
using (StreamReader reader = new StreamReader("file.csv"))
{
String line;
while((line = reader.ReadLine()) != null)
{
lines.add(line);
}
}
//Now you got all lines of your CSV
//Create your file with EPPLUS
foreach(String line in lines)
{
var values = line.Split(';');
foreach(String value in values)
{
//use EPPLUS library to fill your file
}
}