rails/rails — pull request #12038 by SamSaffron (2013-08-27 00:21:12+00:00)
Title: Perf: memoize serialized column list and time zone column list

During profiling a huge reason AR 4 performance degraded was the huge amount of call decorate_columns is getting.

Essentially for every row that AR materializes it calls #decorate_columns via #instantiate in persistance.rb

The following patch memoizes the list of time zone and serialized columns to heavily speed up object materialization.