diff --git a/src/api/server_server.rs b/src/api/server_server.rs
index 7eb4d7cf..277c971d 100644
--- a/src/api/server_server.rs
+++ b/src/api/server_server.rs
@@ -88,15 +88,15 @@ pub(crate) async fn get_server_version_route(
 // Response type for this endpoint is Json because we need to calculate a
 // signature for the response
 pub(crate) async fn get_server_keys_route() -> Result<impl IntoResponse> {
-	let mut verify_keys: BTreeMap<OwnedServerSigningKeyId, VerifyKey> = BTreeMap::new();
-	verify_keys.insert(
+	let verify_keys: BTreeMap<OwnedServerSigningKeyId, VerifyKey> = BTreeMap::from([(
 		format!("ed25519:{}", services().globals.keypair().version())
 			.try_into()
 			.expect("found invalid server signing keys in DB"),
 		VerifyKey {
 			key: Base64::new(services().globals.keypair().public_key().to_vec()),
 		},
-	);
+	)]);
+
 	let mut response = serde_json::from_slice(
 		get_server_keys::v2::Response {
 			server_key: Raw::new(&ServerSigningKeys {
@@ -375,14 +375,11 @@ pub(crate) async fn send_transaction_message_route(
 							.any(|member| member.server_name() == user_id.server_name())
 						{
 							for event_id in &user_updates.event_ids {
-								let mut user_receipts = BTreeMap::new();
-								user_receipts.insert(user_id.clone(), user_updates.data.clone());
+								let user_receipts = BTreeMap::from([(user_id.clone(), user_updates.data.clone())]);
 
-								let mut receipts = BTreeMap::new();
-								receipts.insert(ReceiptType::Read, user_receipts);
+								let receipts = BTreeMap::from([(ReceiptType::Read, user_receipts)]);
 
-								let mut receipt_content = BTreeMap::new();
-								receipt_content.insert(event_id.to_owned(), receipts);
+								let receipt_content = BTreeMap::from([(event_id.to_owned(), receipts)]);
 
 								let event = ReceiptEvent {
 									content: ReceiptEventContent(receipt_content),
@@ -633,13 +630,17 @@ pub(crate) async fn get_backfill_route(body: Ruma<get_backfill::v1::Request>) ->
 		.max()
 		.ok_or_else(|| Error::BadRequest(ErrorKind::InvalidParam, "Event not found."))?;
 
-	let limit = body.limit.min(uint!(100));
+	let limit = body
+		.limit
+		.min(uint!(100))
+		.try_into()
+		.expect("UInt could not be converted to usize");
 
 	let all_events = services()
 		.rooms
 		.timeline
 		.pdus_until(user_id!("@doesntmatter:conduit.rs"), &body.room_id, until)?
-		.take(limit.try_into().unwrap());
+		.take(limit);
 
 	let events = all_events
 		.filter_map(Result::ok)
@@ -685,11 +686,17 @@ pub(crate) async fn get_missing_events_route(
 		.event_handler
 		.acl_check(origin, &body.room_id)?;
 
-	let mut queued_events = body.latest_events.clone();
-	let mut events = Vec::new();
+	let limit = body
+		.limit
+		.try_into()
+		.expect("UInt could not be converted to usize");
 
-	let mut i = 0;
-	while i < queued_events.len() && events.len() < u64::from(body.limit) as usize {
+	let mut queued_events = body.latest_events.clone();
+	// the vec will never have more entries the limit
+	let mut events = Vec::with_capacity(limit);
+
+	let mut i: usize = 0;
+	while i < queued_events.len() && events.len() < limit {
 		if let Some(pdu) = services().rooms.timeline.get_pdu_json(&queued_events[i])? {
 			let room_id_str = pdu
 				.get("room_id")