According to my memory, recently the numbers for chromium/src repo are:

bootstrap: 7 minutes = 3 (download) + 3 (decompress) + 1 minute (incremental fetch). Can be even faster if decompress on the fly.

git clone: 15..20+ minutes = I-don't-know-exactly-why

Plan:
  Use patched git client with extra tracing on canary tasks.