gRPC vs HTTP
The OpenTelemetry Collector that is packaged as part of the ObserveNow Agent supports multiple different formats to consoue telemetry data. The 2 most popular among these are gRPC (port 4317) and HTTP (port 4318). Depending on the support provided by the application SDK, you can choose to use either of the 2 protocols.
HTTP, in general, is more easy to work with and consumes slightly less CPU overall, and is useful if your OTel Collector is exposed via a L7 HTTP load balancer (which does not support gRPC)
gRPC on the other hand is what OpenTelemetry insists on every SDK/Collector supporting, and as such, the spec for gRPC OTel is more deeply defined and stable. However, gRPC can be a larger dependency for your application/SDK, especially if you are trying to manually instrument.
As such, both protocols do have their own merits, and this is something that you should keep in mind when deciding which protocol to use.
The OTel Collector packaged within ObserveNow has support for gzip compression as well. While the decision to use gRPC/HTTP may not have too much performance impact, the decision to use compression is more likely to have an impact on your tracing pipeline performance.