Renaming all the drivers & ekrn and unregistering ESET from WFP did not solve the problem.
But changing the value TcpAckFrequency from 1 to 2 solved the problem!
This is the situation now (all ESET drivers activated, ie not renamed) :
NOTE: as You can see, following the path HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\ I found a lot of sub-folders, so I changed the value TcpAckFrequency from 1 to 2 for for each of them. Can this affect my PC performance/security? What does it have to do with ESET?
Paolo Pichierri received kudos from peteyt in ESET drastically slows the connection speed under a VPN