Mongoid3.1.6rails3.2.21MongoDB2.4.9我们发现find()与where().first存在奇怪的性能问题:$railsc2.1.5:001>Benchmark.ms{User.find('5091e4beccbce30200000006')}=>7.952.1.5:002>Benchmark.ms{User.find('5091e4beccbce30200000006')}=>0.275999999999999972.1.5:003>Benchmark.ms{User.find('5091e4beccbce30200000006')}=>0.2152.1