Topic: Lazy Rails?

I'm trying to figure out where Rails spends most of its time, as my production.log is highly confusing. Both "Rendering" and "DB" are low, but the "Completed in" is about 10 times as high. So what does Rails do, if it doesn't render or access the db?

Here's a few examples:

Completed in 0.16097 (6 reqs/sec) | Rendering: 0.00016 (0%) | DB: 0.02021 (12%) | 200 OK
Completed in 0.22121 (4 reqs/sec) | Rendering: 0.00016 (0%) | DB: 0.01111 (5%) | 200 OK
Completed in 0.14709 (6 reqs/sec) | Rendering: 0.00017 (0%) | DB: 0.01246 (8%) | 200 OK

Thanks.