When you're 90ms into your bid calc and Go pauses for 10ms STW you will loose all your connections and timeout your bids.

It's fine for basic stuff but if you want to really listen to full RTB bid stream and have real time responses you need pauseless GC to win. Or you have to budget for considerably less time to make a decision.

Also there are places in RTB where you have 10ms RTT and Go fails ought right in that situation at scale. :-)