Performance seems much worse in mongo-ruby-driver than Moped 2.

Using localhost with a single mongod behind a mongos. Collection is sharded on {_id: hashed}, testing against the same document in both scenarios.

Update one:

Here's Moped 2:
2.2.1 :049 > puts(Benchmark.measure do
2.2.1 :050 > 1000.times do
2.2.1 :051 > User.collection.find(:_id => u.id).update(:$set => {:foo => "bar"})
2.2.1 :052?> end
2.2.1 :053?> end)
0.340000 0.040000 0.380000 ( 0.608091)
=> nil
2.2.1 :054 > puts(Benchmark.measure do
2.2.1 :055 > 1000.times do
2.2.1 :056 > User.collection.find(:_id => u.id).update(:$set => {:foo => "bar"})
2.2.1 :057?> end
2.2.1 :058?> end)
0.390000 0.040000 0.430000 ( 0.660600)
=> nil
2.2.1 :059 > puts(Benchmark.measure do
2.2.1 :060 > 1000.times do
2.2.1 :061 > User.collection.find(:_id => u.id).update(:$set => {:foo => "bar"})
2.2.1 :062?> end
2.2.1 :063?> end)
0.340000 0.040000 0.380000 ( 0.619269)
<code>

Here's mongo-ruby-driver 2.2:

<code>
2.2.1 :002 > puts(Benchmark.measure do
2.2.1 :003 > 1000.times do
2.2.1 :004 > User.collection.find(:_id => u.id).update_one(:$set => {:foo => "bar"})
2.2.1 :005?> end
2.2.1 :006?> end)
0.580000 0.080000 0.660000 ( 0.882487)
=> nil
2.2.1 :007 > puts(Benchmark.measure do
2.2.1 :008 > 1000.times do
2.2.1 :009 > User.collection.find(:_id => u.id).update_one(:$set => {:foo => "bar"})
2.2.1 :010?> end
2.2.1 :011?> end)
0.560000 0.070000 0.630000 ( 0.834886)
=> nil
2.2.1 :012 > puts(Benchmark.measure do
2.2.1 :013 > 1000.times do
2.2.1 :014 > User.collection.find(:_id => u.id).update_one(:$set => {:foo => "bar"})
2.2.1 :015?> end
2.2.1 :016?> end)
0.540000 0.070000 0.610000 ( 0.794423)
<code>

Just a simple find one:

Moped 2:

<code>
2.2.1 :064 > puts(Benchmark.measure do
2.2.1 :065 > 1000.times do
2.2.1 :066 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :067?> end
2.2.1 :068?> end)
0.360000 0.030000 0.390000 ( 0.494093)
=> nil
2.2.1 :069 > puts(Benchmark.measure do
2.2.1 :070 > 1000.times do
2.2.1 :071 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :072?> end
2.2.1 :073?> end)
0.320000 0.040000 0.360000 ( 0.443336)
=> nil
2.2.1 :074 > puts(Benchmark.measure do
2.2.1 :075 > 1000.times do
2.2.1 :076 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :077?> end
2.2.1 :078?> end)
0.360000 0.040000 0.400000 ( 0.488459)
=> nil
<code>

mongo-ruby-driver 2.2:

<code>
2.2.1 :012 > puts(Benchmark.measure do
2.2.1 :013 > 1000.times do
2.2.1 :014 > User.collection.find(:_id => u.id).update_one(:$set => {:foo => "bar"})
2.2.1 :015?> end
2.2.1 :016?> end)
0.540000 0.070000 0.610000 ( 0.794423)
=> nil
2.2.1 :017 > puts(Benchmark.measure do
2.2.1 :018 > 1000.times do
2.2.1 :019 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :020?> end
2.2.1 :021?> end)
0.530000 0.060000 0.590000 ( 0.692157)
=> nil
2.2.1 :022 > puts(Benchmark.measure do
2.2.1 :023 > 1000.times do
2.2.1 :024 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :025?> end
2.2.1 :026?> end)
0.580000 0.070000 0.650000 ( 0.763661)
=> nil
2.2.1 :027 > puts(Benchmark.measure do
2.2.1 :028 > 1000.times do
2.2.1 :029 > User.collection.find(:_id => u.id).limit(1).entries.first
2.2.1 :030?> end
2.2.1 :031?> end)
0.580000 0.060000 0.640000 ( 0.762495)
<code>