If you look back through this thread you will see that I logged a ticket with support. This is essentially what I got back after sending support my log files:
The reason you’re not able to fully utilize the draft is because of delayed packets. Basically, the data being sent to your trainer is being delayed enough that it is switching back and forth between drafting and not, negating the effects. …All online games, including Zwift, run best at 50ms or lower. The higher your ping, the more issues you’re going to see since it increases the delay between the Zwift servers are your computer
For your information I measured my network latency from here in the UK to some servers in Los Angeles, and it comes out at 150ms. Way outside the recommendation. My conclusion is that I am geographically too far from the Zwift servers to feel the benefit of drafting. 
You can test your speeds here: http://www.speedtest.net/(http://www.speedtest.net/). Try the speed test against a server on the US west coast (Zwift are located near Los Angeles).
I received the same answer: my network latency of 200 ms to USA server prevents proper drafting (in fact, for me it works, but in very, very rare cases). This means that drafting is not available in most of the cases, because most of the people placed at a distance above 2000 km (roughly) to the server in California have issues with drafting, due to a network latency above 50ms.
It is very annoying especially in Zwift races, when you “kill” your legs with 4 W/kg and you see the other guys overtaking you easily at 2.8 - 3 W/kg.
Yep, I believe that Zwift is hosted by AWS. They should ask Amazon to stand up some servers in Europe and the Far East. Then races could be organised based on geographical proximity to the data centres, this would give everyone in the race the chance to draft.
Sadly without drafting all races on Zwift for folks outside the US are just a mass start time trial.
I see some people not based in the US talking about drafting and how great it is. I can only assume they are suffering from “the kings new clothes” syndrome.
Despite all this I still really like Zwift.
Tim,
Ahhh. I missed that. That’s very interesting. Makes sense. I’m in the Northeast US, and my ping is around 80ms to most LA based servers. I often see other people seeming to get much greater draft benefit in the same race (my 95%output is much higher than people who beat me) . If they are using strictly the west coast AWS servers, that can make a big difference.
That explains a lot. Definitely a serious issue for Zwift.
Zero drafting benefit. And low latency for me. Any answer from Zwift?
Btw, drafting benefit in real life are very visible at relatively low speed and result into a 30% wattage benefit. Irrespective of the bike.
Definitely not realistic.
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I agree that it’s not realistic. I doubt it can be made even close to realistic unless everyone has the same trainer…
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I’m just posting here as I suffer the same issue being based in the UK. (KICKR AND STAGES) Not only is drafting extremely rare and sketchy, I also suffer more because I’m lightweight at 137lbs.
In races, not only do I suffer poor or zero draft effect but if for example I’m in a breakaway of say 10 riders and we all ride through a couple of guys who are just on the course doing their own thing - I’ll all of a sudden just lock onto their wheel and the group I was riding with will simply drive off into the distance unless I then unleash a crazy burst of something like 6w-7w/kg to snap off the slow wheel and fight to get back into the pack I was riding in! EXTREMELY FRUSTRATING when you’re already on the limit and no one elses w/kg figures are having to fluctuate like mine.
I’m an A rider and race in the UK and trying to race in the correct group is impossible as I’m forced to also perform high intensity intervals when just sat in the bunch! 
Craig: Being cut off from the draft while passing other riders was also the subject of this recent thread: https://support.zwift.com/hc/en-us/community/posts/115003183871-Rider-gets-stuck-on-another-rider .
Riding around yesterday with another Zwift, for instance – just riding, not a race – we’re rotating being in the wind, and we pass other riders, and often the one of us in second position drops off the draft and a gap forms, and the person in front needs to ease off to allow the person in second to catch back on while pedaling the same power. IRL the person in the draft just follows the person in the wind and there’s no problem.