We had this effect one of our gaming websites, but in reverse: we accidentally added around 900ms to every page load. Gameplays dropped by around 15%. We removed what was causing this and they instantly went back up.
People played it mostly during breaks: lunch breaks (our peak load was during lunch hours in the US), "smoke breaks", etc. So they didn't have a goal, they just had time to spend doing something. Each gameplay took anywhere from 1-5 minutes. Users averaged to 5 plays per day. Our guess was the extra load time caused people to hit some exactly poor threshhold where they were able to play 1 less game during their time allotment.
Edit: we were curious and A/B tested it and saw the effect too. We didn't run it for too long, but a 15% difference is quick to verify when you're measuring something that happens 35 million times per day.
Perfect example of why understanding your domain is so critical to analytics. There are some key assumptions that need to be made before any thing is explored. Love it.
People played it mostly during breaks: lunch breaks (our peak load was during lunch hours in the US), "smoke breaks", etc. So they didn't have a goal, they just had time to spend doing something. Each gameplay took anywhere from 1-5 minutes. Users averaged to 5 plays per day. Our guess was the extra load time caused people to hit some exactly poor threshhold where they were able to play 1 less game during their time allotment.
Edit: we were curious and A/B tested it and saw the effect too. We didn't run it for too long, but a 15% difference is quick to verify when you're measuring something that happens 35 million times per day.