🚀 go-pugleaf

I am sorry but I just don't get it.  So here I go again...

I have written code in Windows98 to talk to COM1 with calls like these:
   TransmitCommChar(hComm, 'w'); Sleep(1);
   TransmitCommChar(hComm, '0'); Sleep(1);
   TransmitCommChar(hComm, '1'); Sleep(1);
The entire source code is at:
http://www.sscnet.ucla.edu/geog/gessler/borland/ezio-stepper-accelerator.txt

It works superbly in Windows98 but like molasses in WindowsXP.

On Windows98, 200 sets of calls to hComm take  9 seconds.
On WindowsXP, 200 sets of calls to hComm take 81 seconds.

On Windows98, these calls modified by Sleep() ranging from 2 to 10 milliseconds take:
1.0, 2.2, 3.2, 3.7, and 4.5 seconds.

On WindowsXP, these identical calls modified by Sleep() ranging from 2 to 10 milliseconds take:
13, 12, 13, 13, and 12 seconds.

QUESTION ONE:  Why does the identical code run slower on XP?

Admittedly, I know next to nothing about talking to COM1 from Windows.  Newsgroup members no doubt wisely recommended that I use WriteFile() and I have tried to modify my code to do just that with no examples to work from and absolutely NO success.

Could someone please provide me with a few simple sample lines of code?  All I want to do is write and read 2-3 ASCII bytes at a time.  Perhaps I need some handshaking, but maybe I don't even need that.  I don't think I need multithreading.  

Could someone also please point me to a tutorial for "Dummies" on this?  All I find on the Web is overkill, pages of code where I only need a few lines.  Yes, I'm impressed that someone can write all that, but it's way too much for my needs.

Isn't there a simple WriteFile() substitute for one simple line:
TransmitCommChar(hComm, 'w'); Sleep(1);
???

Thanks,
Nick