I would have to try it from the first day of fresh windows installation, of this way the doubts will end. but the truth is that many antivirus feel like a fully backpack of encyclopedias in plenum career. Gdata had already been marked as a heavyweight in stage.
if you want to go light EMSISOFT is your only choice but you have to rely on WINDOWS FIREWALL or install another firewall. In that case you only have three good choices ; COMODO , ZoneAlarm or just go with Windows firewall control .If you already know GDATA and TRUSTPORT are very heavy but they both offer just as good protection. DrWeb is not my cup of tea .
I voted for EIS. Some years ago I used dr. web but I was disappointed by it. Too slow in scanning, slows down system, many blocked sites I had to put in exclusion list. Also had experience with gdata/trustport but didn't like them.