To an extent yes; if the page caches the captcha image or value it could invalidate or cause the image to fail. The captcha image is generated on the fly. I don't recommend site side caching. If caching is going to be used you should contact your host and have them enable some form of server side caching assuming they support any. Site side caching just results in outdate and inaccurate data displayed. Performance gained is usually minimal unless you've many queries that are duplicated and ran over and over per page load.