Rails view render weird slowness

Question

The problem

All of the sudden my rails app started to take about 60 seconds serving the initial request and sequential requests if something was changed in assets.

What did I try

There is a lot of answers on SO regarding "rails, render, slow", but none of them helped, because problem seems to be in different area.

Then I tried to rollback gem versions to older point, where this problem didn't exist. No luck. I didn't update anything in the system(rvm, homebrew), so there was nothing to rollback to.

Then I installed ruby-prof profiler and saw that rails spent all the time executing V8::C::String#Utf8Value, but I can't get anything from it.

Diagnostic info

I use OSX Mavericks.

server log:

Started GET "/" for 127.0.0.1 at 2014-04-08 05:30:49 +0200 Processing by HomeController#index as HTML User Load (0.3ms) SELECT "users".* FROM "users" WHERE "users"."id" = 1 ORDER BY "users"."id" ASC LIMIT 1 Rendered home/index.html.erb within layouts/application (64211.8ms) Completed 200 OK in 64248ms (Views: 64218.0ms | ActiveRecord: 2.1ms)

profiler log(scroll horizontally):

 %total   %self      total       self       wait      child            calls    Name
--------------------------------------------------------------------------------
                     61.042      0.000      0.000     61.042              2/2      V8::Conversion::Fundamental#to_ruby
  87.50%   0.00%     61.042      0.000      0.000     61.042                2      V8::Conversion::NativeString#to_ruby
                     61.042     61.042      0.000      0.000              2/2      V8::C::String#Utf8Value
--------------------------------------------------------------------------------
                     61.042     61.042      0.000      0.000              2/2      V8::Conversion::NativeString#to_ruby
  87.50%  87.50%     61.042     61.042      0.000      0.000                2      V8::C::String#Utf8Value
--------------------------------------------------------------------------------
                      8.528      0.000      0.000      8.528              4/4      Proc#call
  12.22%   0.00%      8.528      0.000      0.000      8.528                4      V8::Error::Try#try
                      8.528      0.000      0.000      8.528              4/4      <Module::V8::C>#TryCatch
--------------------------------------------------------------------------------

ok, so putting `config.assets.js_compressor = nil` in `development.rb` resolves this issue obviously. For production it's not so important since it only increases deploy duration a bit. But still.. weird. Or maybe it is normal for rails, and I just reached critical mass of assets number. — Anri, Apr 08 '14 at 04:20
Might be the server performance is degraded.If you are looking to speed up the server then i would say to prefer this gem https://github.com/thedarkone/rails-dev-boost — Pavan, Apr 08 '14 at 04:44
This seems to be an answer http://stackoverflow.com/questions/9573818/rubyracer-v8-binding-for-ruby-performs-really-slow not very promising though - string copy between ruby and v8 is slow. — Anri, Apr 08 '14 at 04:47

Rails view render weird slowness

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