diff --git a/src/api/client/membership.rs b/src/api/client/membership.rs
index 13ff1b92..584f955d 100644
--- a/src/api/client/membership.rs
+++ b/src/api/client/membership.rs
@@ -1249,7 +1249,6 @@ async fn join_room_by_id_helper_remote(
 		services.rooms.timeline.get_pdu(event_id).await.ok()
 	};
 
-	debug!("running stateres check on send_join parsed PDU");
 	let auth_check = state_res::event_auth::auth_check(
 		&state_res::RoomVersion::new(&room_version_id)?,
 		&parsed_join_pdu,
diff --git a/src/core/config/mod.rs b/src/core/config/mod.rs
index bfe0c450..a58bcfe5 100644
--- a/src/core/config/mod.rs
+++ b/src/core/config/mod.rs
@@ -1828,7 +1828,7 @@ pub struct Config {
 	/// setting a non-zero value.
 	///
 	/// default: 0
-	#[serde(default = "default_sender_workers")]
+	#[serde(default)]
 	pub sender_workers: usize,
 
 	/// Enables listener sockets; can be set to false to disable listening. This
@@ -2315,8 +2315,6 @@ fn default_stream_width_scale() -> f32 { 1.0 }
 
 fn default_stream_amplification() -> usize { 1024 }
 
-fn default_sender_workers() -> usize { 4 }
-
 fn default_client_receive_timeout() -> u64 { 75 }
 
 fn default_client_request_timeout() -> u64 { 180 }
diff --git a/src/core/matrix/state_res/mod.rs b/src/core/matrix/state_res/mod.rs
index ea49b29e..a2052b92 100644
--- a/src/core/matrix/state_res/mod.rs
+++ b/src/core/matrix/state_res/mod.rs
@@ -609,7 +609,7 @@ where
 		let fetch_state = |ty: &StateEventType, key: &str| {
 			future::ready(auth_state.get(&ty.with_state_key(key)))
 		};
-		debug!("running auth check on {:?}", event.event_id());
+
 		let auth_result =
 			auth_check(room_version, &event, current_third_party.as_ref(), fetch_state).await;
 
@@ -728,7 +728,7 @@ where
 {
 	let mut room_id = None;
 	while let Some(sort_ev) = event {
-		trace!(event_id = sort_ev.event_id().as_str(), "mainline");
+		debug!(event_id = sort_ev.event_id().as_str(), "mainline");
 		if room_id.is_none() {
 			room_id = Some(sort_ev.room_id().to_owned());
 		}
diff --git a/src/service/rooms/event_handler/handle_outlier_pdu.rs b/src/service/rooms/event_handler/handle_outlier_pdu.rs
index 87b76222..f9889d58 100644
--- a/src/service/rooms/event_handler/handle_outlier_pdu.rs
+++ b/src/service/rooms/event_handler/handle_outlier_pdu.rs
@@ -76,7 +76,7 @@ pub(super) async fn handle_outlier_pdu<'a>(
 		// 5. Reject "due to auth events" if can't get all the auth events or some of
 		//    the auth events are also rejected "due to auth events"
 		// NOTE: Step 5 is not applied anymore because it failed too often
-		debug!("Fetching auth events for {}", incoming_pdu.event_id);
+		debug!("Fetching auth events");
 		Box::pin(self.fetch_and_handle_outliers(
 			origin,
 			&incoming_pdu.auth_events,
@@ -88,12 +88,12 @@ pub(super) async fn handle_outlier_pdu<'a>(
 
 	// 6. Reject "due to auth events" if the event doesn't pass auth based on the
 	//    auth events
-	debug!("Checking {} based on auth events", incoming_pdu.event_id);
+	debug!("Checking based on auth events");
 	// Build map of auth events
 	let mut auth_events = HashMap::with_capacity(incoming_pdu.auth_events.len());
 	for id in &incoming_pdu.auth_events {
 		let Ok(auth_event) = self.services.timeline.get_pdu(id).await else {
-			warn!("Could not find auth event {id} for {}", incoming_pdu.event_id);
+			warn!("Could not find auth event {id}");
 			continue;
 		};
 
@@ -128,7 +128,6 @@ pub(super) async fn handle_outlier_pdu<'a>(
 		ready(auth_events.get(&key))
 	};
 
-	debug!("running auth check to handle outlier pdu {:?}", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&to_room_version(&room_version_id),
 		&incoming_pdu,
diff --git a/src/service/rooms/event_handler/upgrade_outlier_pdu.rs b/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
index 0dca2d70..97d3df97 100644
--- a/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
+++ b/src/service/rooms/event_handler/upgrade_outlier_pdu.rs
@@ -1,6 +1,12 @@
 use std::{borrow::Borrow, collections::BTreeMap, iter::once, sync::Arc, time::Instant};
 
-use conduwuit::{Err, Result, debug, debug_info, err, implement, matrix::{EventTypeExt, PduEvent, StateKey, state_res}, trace, utils::stream::{BroadbandExt, ReadyExt}, warn, info};
+use conduwuit::{
+	Err, Result, debug, debug_info, err, implement,
+	matrix::{EventTypeExt, PduEvent, StateKey, state_res},
+	trace,
+	utils::stream::{BroadbandExt, ReadyExt},
+	warn,
+};
 use futures::{FutureExt, StreamExt, future::ready};
 use ruma::{CanonicalJsonValue, RoomId, ServerName, events::StateEventType};
 
@@ -38,7 +44,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		return Err!(Request(InvalidParam("Event has been soft failed")));
 	}
 
-	debug!("Upgrading pdu {} from outlier to timeline pdu", incoming_pdu.event_id);
+	debug!("Upgrading to timeline pdu");
 	let timer = Instant::now();
 	let room_version_id = get_room_version_id(create_event)?;
 
@@ -46,7 +52,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	//     backwards extremities doing all the checks in this list starting at 1.
 	//     These are not timeline events.
 
-	debug!("Resolving state at event {}", incoming_pdu.event_id);
+	debug!("Resolving state at event");
 	let mut state_at_incoming_event = if incoming_pdu.prev_events.len() == 1 {
 		self.state_at_incoming_degree_one(&incoming_pdu).await?
 	} else {
@@ -64,7 +70,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		state_at_incoming_event.expect("we always set this to some above");
 	let room_version = to_room_version(&room_version_id);
 
-	debug!("Performing auth check to upgrade {}", incoming_pdu.event_id);
+	debug!("Performing auth check");
 	// 11. Check the auth of the event passes based on the state of the event
 	let state_fetch_state = &state_at_incoming_event;
 	let state_fetch = |k: StateEventType, s: StateKey| async move {
@@ -74,7 +80,6 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		self.services.timeline.get_pdu(event_id).await.ok()
 	};
 
-	debug!("running auth check on {}", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&room_version,
 		&incoming_pdu,
@@ -88,7 +93,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		return Err!(Request(Forbidden("Event has failed auth check with state at the event.")));
 	}
 
-	debug!("Gathering auth events for {}", incoming_pdu.event_id);
+	debug!("Gathering auth events");
 	let auth_events = self
 		.services
 		.state
@@ -106,7 +111,6 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 		ready(auth_events.get(&key).cloned())
 	};
 
-	debug!("running auth check on {} with claimed state auth", incoming_pdu.event_id);
 	let auth_check = state_res::event_auth::auth_check(
 		&room_version,
 		&incoming_pdu,
@@ -117,7 +121,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	.map_err(|e| err!(Request(Forbidden("Auth check failed: {e:?}"))))?;
 
 	// Soft fail check before doing state res
-	debug!("Performing soft-fail check on {}", incoming_pdu.event_id);
+	debug!("Performing soft-fail check");
 	let soft_fail = match (auth_check, incoming_pdu.redacts_id(&room_version_id)) {
 		| (false, _) => true,
 		| (true, None) => false,
@@ -214,7 +218,7 @@ pub(super) async fn upgrade_outlier_to_timeline_pdu(
 	// 14. Check if the event passes auth based on the "current state" of the room,
 	//     if not soft fail it
 	if soft_fail {
-		info!("Soft failing event {}", incoming_pdu.event_id);
+		debug!("Soft failing event");
 		let extremities = extremities.iter().map(Borrow::borrow);
 
 		self.services
diff --git a/src/service/rooms/timeline/mod.rs b/src/service/rooms/timeline/mod.rs
index f7925994..74c7348d 100644
--- a/src/service/rooms/timeline/mod.rs
+++ b/src/service/rooms/timeline/mod.rs
@@ -771,7 +771,6 @@ impl Service {
 			ready(auth_events.get(&key))
 		};
 
-		debug!("running auth check on new {} event by {} in {}", pdu.kind, pdu.sender, pdu.room_id);
 		let auth_check = state_res::auth_check(
 			&room_version,
 			&pdu,
@@ -1153,7 +1152,7 @@ impl Service {
 			.boxed();
 
 		while let Some(ref backfill_server) = servers.next().await {
-			info!("Asking {backfill_server} for backfill in {:?}", room_id.to_owned());
+			info!("Asking {backfill_server} for backfill");
 			let response = self
 				.services
 				.sending
@@ -1181,7 +1180,7 @@ impl Service {
 			}
 		}
 
-		warn!("No servers could backfill, but backfill was needed in room {room_id}");
+		info!("No servers could backfill, but backfill was needed in room {room_id}");
 		Ok(())
 	}
 
diff --git a/src/service/sending/mod.rs b/src/service/sending/mod.rs
index ce687551..08ca7010 100644
--- a/src/service/sending/mod.rs
+++ b/src/service/sending/mod.rs
@@ -401,10 +401,16 @@ impl Service {
 
 fn num_senders(args: &crate::Args<'_>) -> usize {
 	const MIN_SENDERS: usize = 1;
-	// Limit the maximum number of senders to the number of cores.
-	let max_senders = available_parallelism();
+	// Limit the number of senders to the number of workers threads or number of
+	// cores, conservatively.
+	let max_senders = args
+		.server
+		.metrics
+		.num_workers()
+		.min(available_parallelism());
 
-	// default is 4 senders. clamp between 1 and core count.
+	// If the user doesn't override the default 0, this is intended to then default
+	// to 1 for now as multiple senders is experimental.
 	args.server
 		.config
 		.sender_workers