Performance degradation when using CrmServiceClient and AuthType OAuth in Dataverse

I've got an MVC.NET solution that calls the Dataverse API and I'm seeing a significant performance degradation when using CrmServiceClient and AuthType=OAuth compared with the (soon to be deprecated) WS-Trust connection (AuthType=Office365)

This is the code used for creating the CrmServiceClient connection (AuthType=OAuth)

var conn = new CrmServiceClient(connectionString);

var service = (IOrganizationService) conn.OrganizationWebProxyClient ?? conn.OrganizationServiceProxy;

and this is the code used for creating WS-Trust connection (AuthType=Office365)

var target = CrmConnection.Parse(connectionString);
            
target.ServiceConfigurationInstanceMode = ServiceConfigurationInstanceMode.PerName; 

var service = (OrganizationService) CrmConfigurationManager.CreateService(target, "DataverseServiceName");

has anyone experienced the same issue?