If the experience was enjoyable for them, they will return. However, if their needs weren't met, they will leave your site in seconds never to return. It's the same experience as when customers walk into a retail store.
Customers expect to be serviced right away and with the least amount of hassle.
This hold true for customers when they visit your Web site also. They want the information on your products and services fast and they aren't going to jump through hoops to get it. Customers aren't going to waste time waiting for your Web site to load either. Time is money for them. The fastest way to lose customers online is to not respond to their needs.