Intranet information retrieval is very important to discover the useful knowledge. In this process, search engine is useful. However, conventional search engines, which are based on centralized architecture, are not suited for the intranet information retrieval because intranet information is frequently updated. Centralized search engines take a long time to collect web pages by robots. So, we have developed a distributed search engine, Cooperative Search Engine (CSE), to retrieve fresh information. In CSE, a local search engine located in each Web server makes an index of local pages. And, a Meta search server integrates these local search engines to realize a global search engine. In such a way, the communication delay occurs at retrieval. So, we have developed several speedup techniques to realize fast retrieval. As this result, we have succeeded in increasing the scalability of CSE. In this paper, we describe these techniques and evaluation.