Ok I missed the part with comodo using different download servers. I have redone my testing and the results are like this file downloaded with WS on 1.7MB/s and 2.32MB with WS off.
I'm thinking about setting up a webserver on a vm and try to test.
Also I would like to ask, does WS do some *in the cloud* scan to possibly take advantage of new signatures that may have not yet been released as update ?