When diagnosing some slow performing visits, I notice the Response time data doesn't quite add up.
For example, I see a user action purepath has a total response time of 5162 ms, made up of 3265 ms Server Contribution and 2 ms of Network contribution. My question is, where is the other ~1800 ms of time being spent? I am unable to locate it. Maybe it is browser render time?
That's basically correct. Any time not accounted for in server time or network time is time spent in browser processing. This could include any calls to other (third-party or CDN) domains. Dynatrace can capture some data on the third-party/CDN contribution, depending on the Dynatrace configuration.