diff --git a/Cargo.lock b/Cargo.lock
index d0a3ced923..633320b36d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -828,6 +828,7 @@ dependencies = [
  "qlog",
  "quinn-udp",
  "regex",
+ "rustc-hash",
  "tokio",
  "url",
 ]
@@ -879,6 +880,7 @@ dependencies = [
  "neqo-qpack",
  "neqo-transport",
  "qlog",
+ "rustc-hash",
  "sfv",
  "test-fixture",
  "url",
@@ -892,6 +894,7 @@ dependencies = [
  "neqo-common",
  "neqo-transport",
  "qlog",
+ "rustc-hash",
  "static_assertions",
  "test-fixture",
 ]
@@ -910,6 +913,7 @@ dependencies = [
  "neqo-crypto",
  "neqo-transport",
  "qlog",
+ "rustc-hash",
  "smallvec",
  "static_assertions",
  "strum",
diff --git a/Cargo.toml b/Cargo.toml
index 016b27f67a..9382aaabd6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,6 +36,7 @@ log = { version = "0.4", default-features = false }
 qlog = { version = "0.13", default-features = false }
 quinn-udp = { version = "0.5.10", default-features = false, features = ["direct-log", "fast-apple-datapath"] }
 regex = { version = "1.9", default-features = false }
+rustc-hash = { version = "1.1", default-features = false, features = [ "std" ]}
 static_assertions = { version = "1.1", default-features = false }
 strum = { version = "0.26", default-features = false, features = ["derive"] }
 url = { version = "2.5", default-features = false, features = ["std"] }
diff --git a/neqo-bin/Cargo.toml b/neqo-bin/Cargo.toml
index ac2e9e581a..cca6694b2f 100644
--- a/neqo-bin/Cargo.toml
+++ b/neqo-bin/Cargo.toml
@@ -39,6 +39,7 @@ neqo-udp = { path = "./../neqo-udp" }
 qlog = { workspace = true }
 quinn-udp = { workspace = true }
 regex = { workspace = true, features = ["unicode-perl"] }
+rustc-hash = { workspace = true }
 tokio = { version = "1", default-features = false, features = ["net", "time", "macros", "rt", "rt-multi-thread"] }
 url = { workspace = true }
 
diff --git a/neqo-bin/src/client/http09.rs b/neqo-bin/src/client/http09.rs
index 0fc600765b..d6bcdcd9e7 100644
--- a/neqo-bin/src/client/http09.rs
+++ b/neqo-bin/src/client/http09.rs
@@ -10,7 +10,7 @@
 
 use std::{
     cell::RefCell,
-    collections::{HashMap, VecDeque},
+    collections::VecDeque,
     fs::File,
     io::{BufWriter, Write as _},
     net::SocketAddr,
@@ -25,6 +25,7 @@ use neqo_transport::{
     CloseReason, Connection, ConnectionEvent, ConnectionIdGenerator, EmptyConnectionIdGenerator,
     Error, Output, RandomConnectionIdGenerator, State, StreamId, StreamType,
 };
+use rustc_hash::FxHashMap as HashMap;
 use url::Url;
 
 use super::{get_output_file, qlog_new, Args, CloseState, Res};
@@ -226,7 +227,7 @@ impl super::Client for Connection {
 impl<'b> Handler<'b> {
     pub fn new(url_queue: VecDeque<Url>, args: &'b Args) -> Self {
         Self {
-            streams: HashMap::new(),
+            streams: HashMap::default(),
             url_queue,
             handled_urls: Vec::new(),
             all_paths: Vec::new(),
diff --git a/neqo-bin/src/client/http3.rs b/neqo-bin/src/client/http3.rs
index 6e8e25c4d5..ad718e963a 100644
--- a/neqo-bin/src/client/http3.rs
+++ b/neqo-bin/src/client/http3.rs
@@ -10,7 +10,7 @@
 
 use std::{
     cell::RefCell,
-    collections::{HashMap, VecDeque},
+    collections::VecDeque,
     fmt::Display,
     fs::File,
     io::{BufWriter, Write as _},
@@ -27,6 +27,7 @@ use neqo_transport::{
     AppError, CloseReason, Connection, EmptyConnectionIdGenerator, Error as TransportError, Output,
     RandomConnectionIdGenerator, StreamId,
 };
+use rustc_hash::FxHashMap as HashMap;
 use url::Url;
 
 use super::{get_output_file, qlog_new, Args, CloseState, Res};
@@ -45,7 +46,7 @@ impl<'a> Handler<'a> {
         let url_handler = UrlHandler {
             url_queue,
             handled_urls: Vec::new(),
-            stream_handlers: HashMap::new(),
+            stream_handlers: HashMap::default(),
             all_paths: Vec::new(),
             args,
         };
diff --git a/neqo-bin/src/client/mod.rs b/neqo-bin/src/client/mod.rs
index fe2b6b9003..f8f39c06db 100644
--- a/neqo-bin/src/client/mod.rs
+++ b/neqo-bin/src/client/mod.rs
@@ -7,7 +7,7 @@
 #![expect(clippy::unwrap_used, reason = "This is example code.")]
 
 use std::{
-    collections::{HashMap, VecDeque},
+    collections::VecDeque,
     fmt::{self, Display},
     fs::{create_dir_all, File, OpenOptions},
     io::{self, BufWriter},
@@ -31,6 +31,7 @@ use neqo_crypto::{
 use neqo_http3::Output;
 use neqo_transport::{AppError, CloseReason, ConnectionId, Version};
 use neqo_udp::RecvBuf;
+use rustc_hash::FxHashMap as HashMap;
 use tokio::time::Sleep;
 use url::{Host, Origin, Url};
 
@@ -528,10 +529,13 @@ const fn local_addr_for(remote_addr: &SocketAddr, local_port: u16) -> SocketAddr
 
 fn urls_by_origin(urls: &[Url]) -> impl Iterator<Item = ((Host, u16), VecDeque<Url>)> {
     urls.iter()
-        .fold(HashMap::<Origin, VecDeque<Url>>::new(), |mut urls, url| {
-            urls.entry(url.origin()).or_default().push_back(url.clone());
-            urls
-        })
+        .fold(
+            HashMap::<Origin, VecDeque<Url>>::default(),
+            |mut urls, url| {
+                urls.entry(url.origin()).or_default().push_back(url.clone());
+                urls
+            },
+        )
         .into_iter()
         .filter_map(|(origin, urls)| match origin {
             Origin::Tuple(_scheme, h, p) => Some(((h, p), urls)),
diff --git a/neqo-bin/src/server/http09.rs b/neqo-bin/src/server/http09.rs
index 72b95adb17..bd4b8b8a0e 100644
--- a/neqo-bin/src/server/http09.rs
+++ b/neqo-bin/src/server/http09.rs
@@ -6,7 +6,7 @@
 
 #![expect(clippy::unwrap_used, reason = "This is example code.")]
 
-use std::{borrow::Cow, cell::RefCell, collections::HashMap, fmt::Display, rc::Rc, time::Instant};
+use std::{borrow::Cow, cell::RefCell, fmt::Display, rc::Rc, time::Instant};
 
 use neqo_common::{event::Provider as _, hex, qdebug, qerror, qinfo, qwarn, Datagram};
 use neqo_crypto::{generate_ech_keys, random, AllowZeroRtt, AntiReplay};
@@ -16,6 +16,7 @@ use neqo_transport::{
     ConnectionEvent, ConnectionIdGenerator, Output, State, StreamId,
 };
 use regex::Regex;
+use rustc_hash::FxHashMap as HashMap;
 
 use super::{qns_read_response, Args};
 use crate::{send_data::SendData, STREAM_IO_BUFFER_SIZE};
@@ -68,8 +69,8 @@ impl HttpServer {
         let is_qns_test = args.shared.qns_test.is_some();
         Ok(Self {
             server,
-            write_state: HashMap::new(),
-            read_state: HashMap::new(),
+            write_state: HashMap::default(),
+            read_state: HashMap::default(),
             is_qns_test,
             regex: if is_qns_test {
                 Regex::new(r"GET +/(\S+)(?:\r)?\n").map_err(|_| Error::Internal)?
diff --git a/neqo-bin/src/server/http3.rs b/neqo-bin/src/server/http3.rs
index 13f07706e0..2cbb315577 100644
--- a/neqo-bin/src/server/http3.rs
+++ b/neqo-bin/src/server/http3.rs
@@ -8,7 +8,6 @@
 
 use std::{
     cell::RefCell,
-    collections::HashMap,
     fmt::{self, Display},
     rc::Rc,
     time::Instant,
@@ -20,6 +19,7 @@ use neqo_http3::{
     Http3OrWebTransportStream, Http3Parameters, Http3Server, Http3ServerEvent, StreamId,
 };
 use neqo_transport::{server::ValidateAddress, ConnectionIdGenerator};
+use rustc_hash::FxHashMap as HashMap;
 
 use super::{qns_read_response, Args};
 use crate::send_data::SendData;
@@ -68,8 +68,8 @@ impl HttpServer {
         }
         Self {
             server,
-            remaining_data: HashMap::new(),
-            posts: HashMap::new(),
+            remaining_data: HashMap::default(),
+            posts: HashMap::default(),
             is_qns_test: args.shared.qns_test.is_some(),
         }
     }
diff --git a/neqo-http3/Cargo.toml b/neqo-http3/Cargo.toml
index 76cd434b5a..62a529603a 100644
--- a/neqo-http3/Cargo.toml
+++ b/neqo-http3/Cargo.toml
@@ -23,6 +23,7 @@ neqo-crypto = { path = "./../neqo-crypto" }
 neqo-qpack = { path = "./../neqo-qpack" }
 neqo-transport = { path = "./../neqo-transport" }
 qlog = { workspace = true }
+rustc-hash = { workspace = true}
 sfv = { version = "0.9", default-features = false }
 url = { workspace = true }
 
diff --git a/neqo-http3/src/connection.rs b/neqo-http3/src/connection.rs
index 2e45dd6430..a7c7c14a2d 100644
--- a/neqo-http3/src/connection.rs
+++ b/neqo-http3/src/connection.rs
@@ -4,13 +4,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::{
-    cell::RefCell,
-    collections::{BTreeSet, HashMap},
-    fmt::Debug,
-    mem,
-    rc::Rc,
-};
+use std::{cell::RefCell, fmt::Debug, mem, rc::Rc};
 
 use neqo_common::{qdebug, qerror, qinfo, qtrace, qwarn, Decoder, Header, MessageType, Role};
 use neqo_qpack::{decoder::QPackDecoder, encoder::QPackEncoder};
@@ -18,6 +12,7 @@ use neqo_transport::{
     streams::SendOrder, AppError, CloseReason, Connection, DatagramTracking, State, StreamId,
     StreamType, ZeroRttState,
 };
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
 
 use crate::{
     client_events::Http3ClientEvents,
@@ -302,7 +297,7 @@ pub struct Http3Connection {
     pub qpack_encoder: Rc<RefCell<QPackEncoder>>,
     pub qpack_decoder: Rc<RefCell<QPackDecoder>>,
     settings_state: Http3RemoteSettingsState,
-    streams_with_pending_data: BTreeSet<StreamId>,
+    streams_with_pending_data: HashSet<StreamId>,
     pub send_streams: HashMap<StreamId, Box<dyn SendStream>>,
     pub recv_streams: HashMap<StreamId, Box<dyn RecvStream>>,
     webtransport: ExtendedConnectFeature,
@@ -333,9 +328,9 @@ impl Http3Connection {
             ),
             local_params: conn_params,
             settings_state: Http3RemoteSettingsState::NotReceived,
-            streams_with_pending_data: BTreeSet::new(),
-            send_streams: HashMap::new(),
-            recv_streams: HashMap::new(),
+            streams_with_pending_data: HashSet::default(),
+            send_streams: HashMap::default(),
+            recv_streams: HashMap::default(),
             role,
         }
     }
diff --git a/neqo-http3/src/control_stream_local.rs b/neqo-http3/src/control_stream_local.rs
index 3f549c959c..a5cc756cea 100644
--- a/neqo-http3/src/control_stream_local.rs
+++ b/neqo-http3/src/control_stream_local.rs
@@ -4,10 +4,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::collections::{HashMap, VecDeque};
+use std::collections::VecDeque;
 
 use neqo_common::{qtrace, Encoder};
 use neqo_transport::{Connection, StreamId, StreamType};
+use rustc_hash::FxHashMap as HashMap;
 
 use crate::{frames::HFrame, BufferedStream, Error, Http3StreamType, RecvStream, Res};
 
diff --git a/neqo-http3/src/features/extended_connect/webtransport_session.rs b/neqo-http3/src/features/extended_connect/webtransport_session.rs
index a7aa2fa7b4..b9df8e2eaf 100644
--- a/neqo-http3/src/features/extended_connect/webtransport_session.rs
+++ b/neqo-http3/src/features/extended_connect/webtransport_session.rs
@@ -4,11 +4,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::{cell::RefCell, collections::BTreeSet, mem, rc::Rc};
+use std::{cell::RefCell, mem, rc::Rc};
 
 use neqo_common::{qtrace, Encoder, Header, MessageType, Role};
 use neqo_qpack::{QPackDecoder, QPackEncoder};
 use neqo_transport::{Connection, DatagramTracking, StreamId};
+use rustc_hash::FxHashSet as HashSet;
 
 use super::{ExtendedConnectEvents, ExtendedConnectType, SessionCloseReason};
 use crate::{
@@ -43,8 +44,8 @@ pub struct WebTransportSession {
     state: SessionState,
     frame_reader: FrameReader,
     events: Box<dyn ExtendedConnectEvents>,
-    send_streams: BTreeSet<StreamId>,
-    recv_streams: BTreeSet<StreamId>,
+    send_streams: HashSet<StreamId>,
+    recv_streams: HashSet<StreamId>,
     role: Role,
 }
 
@@ -89,8 +90,8 @@ impl WebTransportSession {
             state: SessionState::Negotiating,
             frame_reader: FrameReader::new(),
             events,
-            send_streams: BTreeSet::new(),
-            recv_streams: BTreeSet::new(),
+            send_streams: HashSet::default(),
+            recv_streams: HashSet::default(),
             role,
         }
     }
@@ -123,8 +124,8 @@ impl WebTransportSession {
             state: SessionState::Active,
             frame_reader: FrameReader::new(),
             events,
-            send_streams: BTreeSet::new(),
-            recv_streams: BTreeSet::new(),
+            send_streams: HashSet::default(),
+            recv_streams: HashSet::default(),
             role,
         })
     }
@@ -324,7 +325,7 @@ impl WebTransportSession {
         matches!(self.state, SessionState::Active)
     }
 
-    pub fn take_sub_streams(&mut self) -> (BTreeSet<StreamId>, BTreeSet<StreamId>) {
+    pub fn take_sub_streams(&mut self) -> (HashSet<StreamId>, HashSet<StreamId>) {
         (
             mem::take(&mut self.recv_streams),
             mem::take(&mut self.send_streams),
diff --git a/neqo-http3/src/server.rs b/neqo-http3/src/server.rs
index 5a7fdb3668..885d6fe265 100644
--- a/neqo-http3/src/server.rs
+++ b/neqo-http3/src/server.rs
@@ -6,7 +6,6 @@
 
 use std::{
     cell::{RefCell, RefMut},
-    collections::HashMap,
     path::PathBuf,
     rc::Rc,
     time::Instant,
@@ -18,6 +17,7 @@ use neqo_transport::{
     server::{ConnectionRef, Server, ValidateAddress},
     ConnectionIdGenerator, Output,
 };
+use rustc_hash::FxHashMap as HashMap;
 
 use crate::{
     connection::Http3State,
@@ -73,7 +73,7 @@ impl Http3Server {
                 http3_parameters.get_connection_parameters().clone(),
             )?,
             http3_parameters,
-            http3_handlers: HashMap::new(),
+            http3_handlers: HashMap::default(),
             events: Http3ServerEvents::default(),
         })
     }
diff --git a/neqo-qpack/Cargo.toml b/neqo-qpack/Cargo.toml
index ec5aff1222..af11a2a276 100644
--- a/neqo-qpack/Cargo.toml
+++ b/neqo-qpack/Cargo.toml
@@ -20,6 +20,7 @@ log = { workspace = true }
 neqo-common = { path = "./../neqo-common" }
 neqo-transport = { path = "./../neqo-transport" }
 qlog = { workspace = true }
+rustc-hash = { workspace = true }
 static_assertions = { workspace = true }
 
 [dev-dependencies]
diff --git a/neqo-qpack/src/encoder.rs b/neqo-qpack/src/encoder.rs
index 22bc7c9623..30d4db4290 100644
--- a/neqo-qpack/src/encoder.rs
+++ b/neqo-qpack/src/encoder.rs
@@ -4,10 +4,11 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::collections::{HashMap, HashSet, VecDeque};
+use std::collections::VecDeque;
 
 use neqo_common::{qdebug, qerror, qlog::NeqoQlog, qtrace, Header};
 use neqo_transport::{Connection, Error as TransportError, StreamId};
+use rustc_hash::{FxHashMap as HashMap, FxHashSet as HashSet};
 
 use crate::{
     decoder_instructions::{DecoderInstruction, DecoderInstructionReader},
@@ -68,7 +69,7 @@ impl QPackEncoder {
             instruction_reader: DecoderInstructionReader::new(),
             local_stream: LocalStreamState::NoStream,
             max_blocked_streams: 0,
-            unacked_header_blocks: HashMap::new(),
+            unacked_header_blocks: HashMap::default(),
             blocked_stream_cnt: 0,
             use_huffman,
             next_capacity: None,
@@ -385,7 +386,7 @@ impl QPackEncoder {
         let stream_is_blocker = self.is_stream_blocker(stream_id);
         let can_block = self.blocked_stream_cnt < self.max_blocked_streams || stream_is_blocker;
 
-        let mut ref_entries = HashSet::new();
+        let mut ref_entries = HashSet::default();
 
         for iter in h {
             let name = iter.name().as_bytes().to_vec();
diff --git a/neqo-transport/Cargo.toml b/neqo-transport/Cargo.toml
index cb5242244b..d9a10cfacf 100644
--- a/neqo-transport/Cargo.toml
+++ b/neqo-transport/Cargo.toml
@@ -25,6 +25,7 @@ neqo-common = { path = "../neqo-common" }
 neqo-crypto = { path = "../neqo-crypto" }
 mtu = { version = "0.2", default-features = false } # neqo is only user currently, can bump freely
 qlog = { workspace = true }
+rustc-hash = { workspace = true }
 smallvec = { version = "1.13", default-features = false }
 static_assertions = { workspace = true }
 strum = { workspace = true }
diff --git a/neqo-transport/src/server.rs b/neqo-transport/src/server.rs
index 9ed180be95..a99a765c4d 100644
--- a/neqo-transport/src/server.rs
+++ b/neqo-transport/src/server.rs
@@ -9,7 +9,6 @@
 use std::{
     cell::RefCell,
     cmp::min,
-    collections::HashSet,
     ops::{Deref, DerefMut},
     path::PathBuf,
     rc::Rc,
@@ -24,6 +23,7 @@ use neqo_crypto::{
     encode_ech_config, AntiReplay, Cipher, PrivateKey, PublicKey, ZeroRttCheckResult,
     ZeroRttChecker,
 };
+use rustc_hash::FxHashSet as HashSet;
 
 pub use crate::addr_valid::ValidateAddress;
 use crate::{