If gRPC is not installed, this client uses REST over HTTP/1.1. For improved performance, or to make use of the generated clients, we recommend installing the gRPC PHP extension. For installation instructions, [see here](https://cloud.google.com/php/grpc).

NOTE: In addition to the gRPC extension, we recommend installing the protobuf extension for improved performance. For installation instructions, [see here](https://cloud.google.com/php/grpc#install_the_protobuf_runtime_library).