The increasing demand for World Wide Web (WWW) services has made document caching a necessity to decrease download times and reduce Internet traffic. To make efficient use of caching, an instructive conclusion has to be made as to which documents are to be ejected from the cache in case of cache saturation. A processing unit of web caching contains web objects, and changes in the heterogeneity of these web objects and their reference characteristics become a major factor of decreased performance. A provocation of web object heterogeneity more frequently produces a replacement of a web object, but cannot reflect enough characteristics of web object in these traditional replacement techniques. Especially size heterogeneity of an object has an influence on performance of a web caching seriously. In this study, a Response Time Gain Factor is included in this web object replacement algorithm with Size heterogeneity of a web object for performance improvement of the response speed. This factor gives amount of advantage in web cache response time. This is because of Cache. This factor is designed for the average response time gain. With these results, we make a qualitative comparison between these policies and its performance object-hit ratio and an improvement of response speed.