It's hard to say, we have no particular measurement for this. To measure performance decrease on VM you can do the following:
a) measure performance of Matcher on physical server,
b) measure performance of Matcher on VM which is hosted on the same physical computer from a) with access to all host's CPUs and memory and with correct CPU pinning settings (with respect to NUMA CPU allocation and local RAM memory).
Both results should be similar, with approx. 5-10% decrease on VM (depending also on virtualization technology and its configuration).