Client Application Performance

I'm a C# programmer writing an app for work. It's a client app(not web) that will connect to an AWS server via ADO.NET. The server is a large RDS and as I do some testing on my own it works well 1 second or less response time for 1M rows. My concern is the performance if 100 users get connected.

If any one has any experience with this let me know what you think.

Thanks
Randy.