What technical, operational and campaign performance [bidder] KPI’s should be considered when ramping up, and are there any industry benchmarks?
This question was asked on quora, below is my answer.

From a technical perspective you’ll want to measure how many different types of inventory you support: mobile, app, web, video, facebook ads etc… You’ll want to track how many SSPs you’re integrated with and how many impressions are available to you. You should look into creating a feature matrix and decide which advertising features you and your customers find most important.

On the operations side you’ll want to make sure your bidding system is responding to bid requests quickly. The round-trip time for a bid response, from an SSPs perspective, should be no more than 100ms – and even that is pushing it these days. Your internal bidding algorithm should probably make a decision in less than 30 or 40ms. This allows about 60ms for network latency between the bidder and the SSP. Some SSPs have DSP latency monitoring available. This type of monitoring will give you insight into what the SSP is seeing.

Standard tech-op KPIs also apply. Measuring uptime, server health, and especially capacity are important. Figuring out how the system is going to scale will be critical. Measuring capacity against number of bid requests coming in will give you guidance on your infrastructure needs as you ramp up with SSPs.

Campaign KPIs are going to fall in line with traditional online advertising KPIs. Each campaign will typically have a performance goal: total impressions, total clicks, total conversions, etc… The bidding algorithm in a demand side bidder might behave differently for each different type of goal. Some meta-analysis could be done to determine which campaign performance algorithms are performing the best – in other words, determine which type of campaign does well on your system.