Artem,
With the server cach enabled, the map image will not be generated on the fly, instead, it is saved to the disk and the web server just grab and display it. As a result, multi CPU might not help too much (Sure Web Edition works fine on a dual-core or quad-core machine) on the performance but if you have multi servers, that will defenitely contribute more.
Here is some info about how to add the multi server support and improve the performance. The diagram below shows the structure of the whole system, you can see it could have 4 levels, client browser, web site server, wms server and data server.

Here are some tips for using multi servers,
1, Using Multi-Server in WmsOverlay, tile requests WmsOverlay can be spread out to multi-servers, which reduces the works of each wms server.

The following code specifies how to work with four servers in WmsOverlay.
wms.ServerUris.Add(new Uri("wmssamples.thinkgeo.com/WmsServer1.aspx"));
wms.ServerUris.Add(new Uri("wmssamples.thinkgeo.com/WmsServer2.aspx"));
wms.ServerUris.Add(new Uri("wmssamples.thinkgeo.com/WmsServer3.aspx"));
wms.ServerUris.Add(new Uri("wmssamples.thinkgeo.com/WmsServer4.aspx"));
2, Pre-generate cache files,
Our cache system will generate the cache images, you can also pre generate the images with our APIs. Please reference the following link to get more information about cache system. Now we have some resources working on the enhancements and maybe in the coming release, the cached file structure will have a bit difference.
gis.thinkgeo.com/Support/DiscussionForums/tabid/143/aff/20/aft/4893/afv/topic/Default.aspx
3, Build up an image server using pre-generated cache files (shows in the first graph). The 2 adjacent images will always come from different WMS server so the servers’ load will be even. It will be great if there has a good Cache Mechanism on Data Server to speed the performance up.
4, The WMS services on different Servers should be all the same.
You can see with WMS Service, it’s easy to distribute it on multi servers and so it has great possibilities to improve the performance, you do not need to manage the session states also. We tested with the multi-WMS Server (with 2 WMS Servers) and it works fine.
Hope it helps, let me know for any comments.
Thanks,
Ben