Dramatic rendering slowdown from 3.0.3 to 3.0.6

Indeed it does, Santiago, specifically the changes to activerecord/lib/active_record/attribute_methods/read.rb. Reverting those makes my app perform as it did with 3.0.3 (or even a little better, it seems).

I’ve investigated this a bit more and come to the conclusion that rescue is extremely expensive on ruby 1.8. When I run this gist I get the following results on my machine:

Showing results for 1000000 method calls

Method IS NOT defined
=====================
With rescue:      10.35 seconds
With respond_to:  0.64 seconds
Direct call:      0.35 seconds

Method IS defined
=================
With rescue:      0.57 seconds
With respond_to:  0.85 seconds
Direct call:      0.35 seconds

Unless I’m misunderstanding something, it would appear that changing

def read_attribute(attr_name)
  send "_#{attr_name}"
rescue NoMethodError
  _read_attribute attr_name
end

in read.rb to something like

def read_attribute(attr_name)
  if respond_to? "_#{attr_name}"
   send "_#{attr_name}"
  else
    _read_attribute attr_name
  end
end

should improve the speed dramatically when the underscore method doesn’t exist, and only add a slight penalty (the respond_to call) when it does. Any thoughts?

I added a pull request for this change after verifying that the tests pass with it.

(Actually, this test failed, but that appears to be wholly unrelated to my change.)