For A Snappy User Experience, Always Validate On The Client

To avoid unnecessary round trips to the server, validate form entries on the client using JavaScript before posting them. This provides quick feedback and makes your application feel more responsive. Always make sure you explain your validation errors as well. If you use complex password rules or regex patterns, include a message to explain what the rules are to prevent user frustration.

50 Ways to Avoid Find and Fix ASP.NET Performance Issues