silence asset noise in development. Thanks to @joshsusser. @denniscollective said I should put something pithy here, but that sounds like a bad idea.

config/initializers/silence_assets.rb

@@ -0,0 +1,16 @@
+if Rails.env.development?
+
+  Rails.application.assets.logger = Logger.new('/dev/null')
+
+  Rails::Rack::Logger.class_eval do
+    def call_with_quiet_assets(env)
+      previous_level = Rails.logger.level
+      Rails.logger.level = Logger::ERROR if env['PATH_INFO'] =~ %r{^/assets/}
+      call_without_quiet_assets(env)
+    ensure
+      Rails.logger.level = previous_level
+    end
+    alias_method_chain :call, :quiet_assets
+  end
+
+end