google compute engine tool gcloud is exceptionally slow

I just ran into a similar issue myself, though not as bad as minute long response times. What helped me was turning off the usage reporting.

Looking at some timings:

$ gcloud config set disable_usage_reporting False
$ time gcloud compute -h | tail -1
  real  0m7.058s
  user  0m0.464s
  sys   0m0.088s

A whopping 7 secs to access the help!

Fortunately, this improves greatly after disabling reporting:

$ gcloud config set disable_usage_reporting True
$ time gcloud compute -h | tail -1
  real  0m0.541s
  user  0m0.459s
  sys   0m0.080s

Much better!

I traced this back to packet filters. When I deleted this rule #5 in my AT&T Uverse modem/router (Motorola NVG589), everything works ok. This was a default setting in the modem which caused all sorts of issues.