Datastore performance

Something strange with the performance of the AppEngine Datastore. I tried to run the following code:

from google.appengine.ext import db
from time import time

print 'Content-Type: text/plain'
print ''

total_t=time()

class C(db.Model):
 i=db.IntegerProperty()

for i in range(10):
 t=time()
 for j in range(10):
  c=C(i=i)
  c.save()
 print time()-t

print "total time:", time()-total_t

As you can see, this is a complete python module, not dependent on django or anything else. Just add a corresponding mapping to app.yaml and you can try it by yourself. So the output of this code, which adds 100 records to the Datastore is:

0.307200908661
0.279258012772
0.305376052856
0.310864925385
0.286242008209
0.283288002014
0.299383878708
0.286517858505
0.281584024429
0.268044948578
total time: 2.90873217583

I tried to add 200 records, and got a time-out as AppEngine does not allow long-running queries. I had pretty similar timings on the dev_appserver. This is very slow, and I cannot understand where is the catch.