Rails 3 AR performance has regressed since Rails 2

Has there been any update to your issue? I am using Rails 3.0 Beta 4 and am finding it is much slower than Rails 2.3.5

I am using Ruby Enterprise 1.8.7 and Passenger 2.2.15

I go from 5.31 trans/sec to 3.05 trans/sec per AWS EC2 instance.

$ siege -c 5 -t 1M http://localhost

RAILS 2.3.5 RESULTS
Transactions:             320 hits
Availability:          100.00 %
Elapsed time:           60.26 secs
Data transferred:          6.76 MB
Response time:            0.45 secs
Transaction rate:          5.31 trans/sec
Throughput:            0.11 MB/sec
Concurrency:            2.41
Successful transactions:         320
Failed transactions:             0
Longest transaction:          1.05
Shortest transaction:          0.25

RAILS 3
Transactions:             169 hits
Availability:          100.00 %
Elapsed time:           55.38 secs
Data transferred:          3.72 MB
Response time:            1.06 secs
Transaction rate:          3.05 trans/sec
Throughput:            0.07 MB/sec
Concurrency:            3.23
Successful transactions:         169
Failed transactions:             0
Longest transaction:          1.74
Shortest transaction:          0.58

Tried this on a slightly more formal benchmark, with a test script like this:

10.times do
  1000.times{ Post.create(:title => "bla", :body => "x" * 1000) }
  max = Post.maximum(:id)
  1000.times{ Post.find(rand(max) + 1) }
end

Invoked like this:

[21:14:57] miles slopper ~/c/perftest2
$ rake db:drop; rake db:create; rake db:migrate; time ./script/runner -e production ~/tmp/posttest 
...
real    2m12.275s
user    0m41.200s
sys 0m1.640s

and this:

$ rake db:drop; rake db:create; rake db:migrate; time ~/c/rails/bin/rails runner -e production ~/tmp/posttest 
...
real    3m21.563s
user    1m8.380s
sys 0m1.920s

This is with a postgres database on a Ubuntu 10.04 machine. So I'm seeing a similar slowdown. Of course, benchmarking is a notoriously tricky business so it's hard to be sure to what extent this reflects a real-world workload.

This ticket should be merged into this:

https://rails.lighthouseapp.com/projects/8994/tickets/5098-rails-3-...

I don't know how to do it, but the same problem is better identified there.