The image cache normally loads images from the server but you can configure the system so that it makes the respondent's browser cache images that are displayed during the interview. The browser cache can reduce the load on your web servers, but the disadvantage is that changes to templates and images are not picked up immediately after activation.

Image cache caches files are defined by the OutputCache directive in ImageCache.aspx in C:\Inetpub\wwwroot\SPSSMR\ImageCache (or the equivalent folder when installed to a non-default website). ImageCache.aspx is typically defined as:

To cache with the respondent's browser only, change the value of the Location parameter to Client. To cache files on both the web server and the respondent's computer, set Location to ServerAndClient and increase Duration to 600 seconds.

For more information, see the MSDN article “OutputCacheLocation Enumeration”: