If your r/w workload is bigger than shared_buffers, seriously consider enabling backend_flush_after. Both throughput *and* jitter are considerably better with it enabled.pic.twitter.com/PYDSemn5Dg
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Less predictable, doesn't necessarily slow down originator of dirty data, also affects temp files etc where we *want* the kernel to cache dirty data.
So, better not to lower Linux dirty settings too much (for temp files) and rather set background flush after? As usual, this depends on workload 
Yes. Although the best thing still is to separate temporary tablespaces and WAL data onto separate disks. The latency caused by temp file writeback can still cause latency spikes, although it has gotten *much* better in recent kernels, and with SSDs.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.