I have a service running which periodically checks a folder for a file and then processes it. (Reads it, extracts the data, stores it in sql)

So I ran it on a test box and it took a little longer thaan expected. The file had 1.6 million rows, and it was still running after 6 hours (then I went home).

The problem is the box it is running on is now absolutely crippled - remote desktop was timing out so I cant even get on it to stop the process, or attach a debugger to see how far through etc. It's solidly using 90%+ CPU, and all other running services or apps are suffering.

The code is (from memory, may not compile):

List<ItemDTO> items = new List<ItemDTO>();
using (StreamReader sr = fileInfo.OpenText())
{
    while (!sr.EndOfFile)
    {
        string line = sr.ReadLine()
        try {
           string s = line.Substring(0,8);
           double y = Double.Parse(line.Substring(8,7));

           //If the item isnt already in the collection, add it.
           if (items.Find(delegate(ItemDTO i) { return (i.Item == s); }) == null)
               items.Add(new ItemDTO(s,y));
         }
         catch { /*Crash*/ }
    }
    return items;
}

- So I am working on improving the code (any tips appreciated).

But it still could be a slow affair, which is fine, I've no problems with it taking a long time as long as its not killing my server.

So what I want from you fine people is: 1) Is my code hideously un-optimized? 2) Can I limit the amount of CPU my code block may use?

Cheers all