Rails 0.12 (19th April, 2005) added script/profiler to profile a single statement from within the environment.
Moved to script/performance/profiler
Usage:
profiler 'Person.expensive_method(10)' [times]
Examples:
script/performance/profiler 'Person.expensive_method(10)'
script/performance/profiler 'Person.expensive_method(10)' 10 # runs the statement 10 times
$ ruby script/performance/profiler 'User.new' 5
% cumulative self self total
time seconds seconds calls ms/call ms/call name
189.25 1.76 1.76 1 1760.00 1760.00 Profiler__.start_profile
43.01 2.16 0.40 115 3.48 3.91 ActiveRecord::ConnectionAdapters::Column#simplified_type
8.60 2.24 0.08 15 5.33 8.67 Array#each
7.53 2.31 0.07 115 0.61 5.39 ActiveRecord::ConnectionAdapters::Column#initialize
6.45 2.37 0.06 115 0.52 0.52 ActiveRecord::ConnectionAdapters::Column#type_cast
5.38 2.42 0.05 690 0.07 0.07 Regexp#===
...
0.00 2.69 0.00 10 0.00 0.00 Process.times
0.00 2.69 0.00 10 0.00 0.00 Benchmark.times