With the ever-growing web traffic, cluster-based web server is becoming more and more important to the Internet's infrastructure. Making the best use of all the available resources in the cluster to achieve high performance is thus a significant research issue. In this paper, we introduce Cyclone, a cluster-based web server that can achieve nearly optimal throughput. Cyclone makes use of a novel network support mechanism called Socket Cloning (SC), together with the method of hot object replication, to obtain high performance. SC allows an opened socket to be moved efficiently between cluster nodes. With SC, the processing of HTTP requests can be migrated to the node that has a cached copy of the requested document, thus obviating the need for any cache transfer between cluster nodes. To achieve better load balancing, frequently accessed documents (hot objects) are replicated to other cluster nodes. Trace-driven benchmark tests using http_load show that Cyclone outperforms existing approaches and can achieve a throughput of 14575 requests/s (89.5 MBytes/s), which is 98% efficiency of the available network bandwidth, with eight web server nodes.