To reproduce, simply deploy any Nuget package to Artifactory.
Then, you will see in the artifactory.log:
2019-07-10 14:03:36,019 [art-exec-154] [INFO ] (o.j.r.n.NuGetWorkContext:88) - Finished writing Nuget metadata for repo nuget-local on path 'Aviv.1.0.0.nupkg' at 1562756616019 ms
1562756616019 = Wed Jul 10 2019 14:03:36 GMT+0300
Instaed, this log entry should show how much time it took for Artifactory to calculate this package's metadata.