API throttling concerns

My company is migrating from our own proprietary CRM system to Keap. After initially importing our subscribers via the admin site’s CSV import feature, I’m preparing a REST API-based import of customer order data in the form of tags and custom fields for somewhere between 150,000 and 200,000 contacts, with an average of four API calls per contact. I’ve read the API throttling article and I can manage the 125,000 API calls per day and the 25 calls per second limit (I’m using OAUTH), but I’ve seen a troubling issue.

Even during my early testing in which I was getting familiar with your system, my occasional onesie-twosie API calls sometimes received ‘too many requests’ and ‘throttling’ errors, a troubling occurrence for such a trivial exercise of your system. If I’m being throttled after these casual and manually instigated requests, I’m getting a real bad feeling about running an automated process, even with careful coding to not exceed the 125K daily max and the 25 calls per second.

I’ve generally been pleased with the responsiveness of the Keap server. My testing API calls generally return a response within a couple heartbeats. So it doesn’t seem that my once-every-few minutes-or-so API requests can be overloading the server.

How bad is this going to be when I start streaming in the requests, and what kind of techniques might exacerbate this looming problem?