that Microsoft has these optimized to work as good as a physical machine?
Yes, MS has - quite close.
The main problem is that it makes only sense in small installations. The moment your virtual SQL Server requires its own machine with a carefully laid out disk setup - which is any except a small SQL instance with low volume - there is nothing else to really put on that server.
I run a SQL server on a virtualization platform. Out of the 20 disks in that machine 12 are dedicated to the SQL server (for logs & data, including tempdb - the OS loads from a VHD). The next upgrade will take it quite to the limit - even now it is the fattest VM with 16GB RAM of my available 64GB. Once I need to upgrade that.... what sense does it have?
With current technology you are limited to 4 virtual cores - 16 in Hyper-V 3 (coming next year). This is not really a lot for databases analytics. If you do OLAP-type processing, visualization with Hyper-V may simply not scale up enough.
The main problem is thus not that MS can not get close to comparable hardware, but that SQL Servers can get so big that the comparable hardware means a 1 SQL Server on one hardware level anyway, plus you can not scale a VM as good as hardware, sadly.