Inconsistent repository statistics in Admin Center

The statistics returned by the "Compute Statistics" in the admin center returns very different results on consecutive runs.

Example:

• Run1:
  Number of documents 2,977
  Number of versions: 92
  Number of blobs 2,335
  Total size of blobs: 2,128.346
  Max tree depth 10
  Max blob size (KBytes) 166,350.2
  Biggest folder: 182 children
  Average read speed (doc/s): 248

• Run2:
  Number of documents 22,840
  Number of versions: 2,254
  Number of blobs 22,738
  Total size of blobs: 19,847.195
  Max tree depth 15
  Max blob size (KBytes) 476,074.7
  Biggest folder: 204 children
  Average read speed (doc/s): 79