Avoiding BinaryReader.ReadString() in C#?

If you think that reading the file line by line is the bottleneck, and depending on its size, you can try to read it all at once:

// read the entire file at once
string entireFile = System.IO.File.ReadAllText(path);

It this doesn't help, you can try to add a separate thread with a semaphore, which would start reading in background immediately when the program is started, but block the requesting thread at the moment you try to access the data.

This is called a Future, and you have an implementation in Jon Skeet's miscutil library.

You call it like this at the app startup:

// following line invokes "DoTheActualWork" method on a background thread.
// DoTheActualWork returns an instance of MyData when it's done
Future<MyData> calculation = new Future<MyData>(() => DoTheActualWork(path));

And then, some time later, you can access the value in the main thread:

// following line blocks the calling thread until
// the background thread completes
MyData result = calculation.Value;

If you look at the Future's Value property, you can see that it blocks at the AsyncWaitHandle if the thread is still running:

public TResult Value
{
    get
    {
        if (!IsCompleted)
        {
            _asyncResult.AsyncWaitHandle.WaitOne();
            _lock.WaitOne();
        }
        return _value;
    }
}