Welcome to the ODK forum, @khaleedsk ! We're glad you're here. When you get a chance, please Introduce yourself here! I'd also encourage you to add a picture as your avatar because it helps build community!
Regarding your concern…
- Are you running your own Central server? If so, what are it’s specifications? You may need to upgrade your server.
- Can you do an internet speed test on the computer running Excel? How is your connection speed?