Question

I have a list of User objects, and I have to remove ONE item from the list with a specific UserID.

This method has to be as fast as possible, currently I am looping through each item and checking if the ID matches the UserID, if not, then I add the row to a my filteredList collection.

List allItems = GetItems();

for(int x = 0; x < allItems.Count; x++)
{
    if(specialUserID == allItems[x].ID)
        continue;
    else
        filteredItems.Add( allItems[x] );
}

Answer 1

If it really has to be as fast as possible, use a different data structure. List isn’t known for efficiency of deletion. How about a Dictionary that maps ID to User?