I conducted a few test searches, I am getting responses on around 1.5 – 2.5 seconds in average. I would say that is an average/good response time for a webshop site. The response time greatly depends on the web server performance, as well as on some of the correct configuration.
This documentation will walk you through some of the greatest impact changes you can make to get the best possible performance. The more you can apply, the better.