Ok, so I've been using Ubuntu 14.04 for the last half an hour or so, and I do see similar spikes in ping times, and it appears to be in similar intervals as on Win 8.1. However, it hasn't dropped any TCP connection so far, my SSH sessions haven't been interrupted. They do however become slightly lagging for a few seconds while the ping times spike. I have seen ping times even above 600 ms on the local network. I don't have any explanation for such extreme ping times, there is virtually no other network traffic going on on my network, and there is only one other 5ghz network in the neighbourhood that I can tell, and it appears to be far away.
64 bytes from 192.168.0.2: icmp_seq=247 ttl=64 time=1.12 ms
64 bytes from 192.168.0.2: icmp_seq=248 ttl=64 time=1.31 ms
64 bytes from 192.168.0.2: icmp_seq=249 ttl=64 time=1.80 ms
64 bytes from 192.168.0.2: icmp_seq=250 ttl=64 time=0.756 ms
64 bytes from 192.168.0.2: icmp_seq=251 ttl=64 time=1.94 ms
64 bytes from 192.168.0.2: icmp_seq=252 ttl=64 time=160 ms
64 bytes from 192.168.0.2: icmp_seq=253 ttl=64 time=80.8 ms
64 bytes from 192.168.0.2: icmp_seq=254 ttl=64 time=35.6 ms
64 bytes from 192.168.0.2: icmp_seq=255 ttl=64 time=0.936 ms
64 bytes from 192.168.0.2: icmp_seq=256 ttl=64 time=1.26 ms
64 bytes from 192.168.0.2: icmp_seq=257 ttl=64 time=0.737 ms
64 bytes from 192.168.0.2: icmp_seq=258 ttl=64 time=1.44 ms
So, even with Linux I get ping spikes on a regular basis, but no dropped connections.