Flaky DNS/connection issues when using Wi-Fi in Japan. Fifty-percent of page/images load if lucky
Try running Namebench to determine the best DNS entries for your connection.  The project hasn't been updated in awhile but runs fine even on OS X 10.11.2 betas.

If you are constantly switching wireless networks you may want to consider running this regularly to get a sense of what domain name servers are most often available from these different connections.