Most efficient method of reading binary file

Question

I have a binary file of known size that i am trying to parse and place into a treeview object.  I am trying to reduce the amount of time it takes to parse the data, create my objects, and display the data.  I did this using to different methods, and the results were surprising.  i'm wondering if i am doing something wrong here...
Method 1:
Read entire file into byte[]
create new message instance and add to List
continue until entire byte[] is read.
iterate through list using for loop
get msg instance
add tree entry
total time = 4371 miliseconds

Method 2:
read message into byte[]
create new message instance
add tree entry
continue until entire byte array is read
total time = 4098 milliseconds.

Size of message = 2512640 bytes
Number of records = 20381

So if i am looping through a total of 40762 times in method 1, and 20381 times in method 2, how come my times are only marginally better?

Answer 1

It's not the loop that's takes the bulk of the time.  It's reading the file.  I'd be willing to bet that nearly 3.5 seconds of this process is just reading the file itself.  After that, it's just gravy.

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Answer 2

actually, from what i see, the greatest amount of elapsed time is from adding the nodes to the treeview.
My reading of hte file = 3 mil
iterating through list to create msg instances = 78 mil
getting the correct message based index and adding to tree:  4249 mil.

Answer 3

Hello, Jim Green
David is right, reading file frequently will eat you too much time, I/O operations is really time consuming operation, because operating memory is much quicker than operating disk. So if you have enough memory, I recommend you to use your first method.
If you feel it is too slow, I think you could do some optimization.
Thanks
Chao

Answer 4

If you are using Add() to add nodes, are you calling TreeView.BeginUpdate() before updating the TreeView, and TreeView.EndUpdate() afterwards? Otherwise a lot of time will be wasted redrawing the tree view.

(The preferred method is to call AddRange() to add all the nodes at once; perhaps you're already doing that.)