diff --git a/cozo-core/src/runtime/db.rs b/cozo-core/src/runtime/db.rs
index bbef8047..3a407b3b 100644
--- a/cozo-core/src/runtime/db.rs
+++ b/cozo-core/src/runtime/db.rs
@@ -12,7 +12,8 @@ use std::default::Default;
 use std::fmt::{Debug, Formatter};
 use std::path::Path;
 use std::sync::atomic::{AtomicBool, AtomicU32, AtomicU64, Ordering};
-use std::sync::{Arc, Mutex, RwLock};
+use std::sync::{Arc, Mutex};
+use crossbeam::sync::ShardedLock;
 #[allow(unused_imports)]
 use std::thread;
 #[allow(unused_imports)]
@@ -99,7 +100,7 @@ pub struct Db<S> {
     callback_count: Arc<AtomicU32>,
     callback_sender: Sender<(SmartString<LazyCompact>, CallbackOp, NamedRows, NamedRows)>,
     event_callbacks: Arc<
-        RwLock<(
+        ShardedLock<(
             BTreeMap<u32, CallbackDeclaration>,
             BTreeMap<SmartString<LazyCompact>, BTreeSet<u32>>,
         )>,
diff --git a/cozo-core/src/storage/mem.rs b/cozo-core/src/storage/mem.rs
index 3834a262..e5fbc887 100644
--- a/cozo-core/src/storage/mem.rs
+++ b/cozo-core/src/storage/mem.rs
@@ -13,7 +13,8 @@ use std::default::Default;
 use std::iter::Fuse;
 use std::mem;
 use std::ops::Bound;
-use std::sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard};
+use std::sync::{Arc};
+use crossbeam::sync::{ShardedLock, ShardedLockReadGuard, ShardedLockWriteGuard};
 
 use itertools::Itertools;
 use miette::{bail, Result};
@@ -37,7 +38,7 @@ pub fn new_cozo_mem() -> Result<crate::Db<MemStorage>> {
 /// The non-persistent storage
 #[derive(Clone, Default)]
 pub struct MemStorage {
-    store: Arc<RwLock<BTreeMap<Vec<u8>, Vec<u8>>>>,
+    store: Arc<ShardedLock<BTreeMap<Vec<u8>, Vec<u8>>>>,
 }
 
 impl<'s> Storage<'s> for MemStorage {
@@ -98,9 +99,9 @@ impl<'s> Storage<'s> for MemStorage {
 }
 
 pub enum MemTx<'s> {
-    Reader(RwLockReadGuard<'s, BTreeMap<Vec<u8>, Vec<u8>>>),
+    Reader(ShardedLockReadGuard<'s, BTreeMap<Vec<u8>, Vec<u8>>>),
     Writer(
-        RwLockWriteGuard<'s, BTreeMap<Vec<u8>, Vec<u8>>>,
+        ShardedLockWriteGuard<'s, BTreeMap<Vec<u8>, Vec<u8>>>,
         BTreeMap<Vec<u8>, Option<Vec<u8>>>,
     ),
 }
diff --git a/cozo-core/src/storage/sqlite.rs b/cozo-core/src/storage/sqlite.rs
index 7e7c04b7..13ac6e06 100644
--- a/cozo-core/src/storage/sqlite.rs
+++ b/cozo-core/src/storage/sqlite.rs
@@ -7,7 +7,8 @@
  */
 
 use std::path::{Path, PathBuf};
-use std::sync::{Arc, Mutex, RwLock, RwLockReadGuard, RwLockWriteGuard};
+use std::sync::{Arc, Mutex};
+use crossbeam::sync::{ShardedLock, ShardedLockReadGuard, ShardedLockWriteGuard};
 
 use ::sqlite::Connection;
 use either::{Either, Left, Right};
@@ -23,7 +24,7 @@ use crate::utils::swap_option_result;
 /// The Sqlite storage engine
 #[derive(Clone)]
 pub struct SqliteStorage {
-    lock: Arc<RwLock<()>>,
+    lock: Arc<ShardedLock<()>>,
     name: PathBuf,
     pool: Arc<Mutex<Vec<ConnectionWithFullMutex>>>,
 }
@@ -139,7 +140,7 @@ impl<'s> Storage<'s> for SqliteStorage {
 }
 
 pub struct SqliteTx<'a> {
-    lock: Either<RwLockReadGuard<'a, ()>, RwLockWriteGuard<'a, ()>>,
+    lock: Either<ShardedLockReadGuard<'a, ()>, ShardedLockWriteGuard<'a, ()>>,
     storage: &'a SqliteStorage,
     conn: Option<ConnectionWithFullMutex>,
     stmts: [Mutex<Option<Statement<'a>>>; N_CACHED_QUERIES],
@@ -168,7 +169,7 @@ const SKIP_RANGE_QUERY: usize = 5;
 
 impl Drop for SqliteTx<'_> {
     fn drop(&mut self) {
-        if let Right(RwLockWriteGuard { .. }) = self.lock {
+        if let Right(ShardedLockWriteGuard { .. }) = self.lock {
             if !self.committed {
                 let query = r#"rollback;"#;
                 let _ = self.conn.as_ref().unwrap().execute(query);
@@ -252,7 +253,7 @@ impl<'s> StoreTx<'s> for SqliteTx<'s> {
     }
 
     fn commit(&mut self) -> Result<()> {
-        if let Right(RwLockWriteGuard { .. }) = self.lock {
+        if let Right(ShardedLockWriteGuard { .. }) = self.lock {
             if !self.committed {
                 let query = r#"commit;"#;
                 let mut statement = self.conn.as_ref().unwrap().prepare(query).unwrap();