Hi Peter,
I've talked with the core engineering team about this, and they will
investigate the performance issues you encountered in this scenario.
In general the benefits of the BulkMutateJobService are:
* Operations are automatically applied at an optimal rate, avoiding
operation rate limit errors.
* HTTPS connections to the AdWords servers don't need to remain open
while the work is being done.
* It's cheaper.
Best,
- Eric