A Web crawler is an important component of the Web search engine. It demands large amount of hardware resources (CPU and memory) to crawl data from the rapidly growing and changing Web. So that the crawling process should be a continuous process performed from time-to-time to maintain up-to-date crawled data. This paper develops and investigates the performance of a new approach to speed up the crawling process on a multi-core processor through virtualization. In this approach, the multi-core processor is divided into a number of virtual-machines (VMs) that can run in parallel (concurrently) performing different crawling tasks on different data. It presents a description, implementation, and evaluation of a VM-based distributed Web crawler. In order to estimate the speedup factor achieved by the VM-based crawler over a non-virtualization crawler, extensive crawling experiments were carried-out to estimate the crawling times for various numbers of documents. Furthermore, the average crawling rate in documents per unit time is computed, and the effect of the number of VMs on the speedup factor is investigated. For example, on an Intel® Core™ i5-2300 CPU @2.80 GHz and 8 GB memory, a speedup factor of ~1.48 is achieved when crawling 70000 documents on 3 and 4 VMs.