diff --git a/bytecode/src/lib.rs b/bytecode/src/lib.rs
index 691bd507a8..b4cfa42922 100644
--- a/bytecode/src/lib.rs
+++ b/bytecode/src/lib.rs
@@ -1075,7 +1075,7 @@ impl<C: Constant> fmt::Debug for CodeObject<C> {
     }
 }
 
-#[derive(Serialize, Deserialize)]
+#[derive(Serialize, Deserialize, Debug)]
 pub struct FrozenModule<C: Constant = ConstantData> {
     #[serde(bound(
         deserialize = "C: serde::Deserialize<'de>, C::Name: serde::Deserialize<'de>",
@@ -1084,3 +1084,132 @@ pub struct FrozenModule<C: Constant = ConstantData> {
     pub code: CodeObject<C>,
     pub package: bool,
 }
+
+pub mod frozen_lib {
+    use super::*;
+    use bincode::{options, Options};
+    use std::convert::TryInto;
+    use std::io;
+
+    pub fn decode_lib(bytes: &[u8]) -> FrozenModulesIter {
+        let data = lz4_flex::decompress_size_prepended(bytes).unwrap();
+        let r = VecReader { data, pos: 0 };
+        let mut de = bincode::Deserializer::with_bincode_read(r, options());
+        let len = u64::deserialize(&mut de).unwrap().try_into().unwrap();
+        FrozenModulesIter { len, de }
+    }
+
+    pub struct FrozenModulesIter {
+        len: usize,
+        // ideally this could be a SeqAccess, but I think that would require existential types
+        de: bincode::Deserializer<VecReader, bincode::DefaultOptions>,
+    }
+
+    impl Iterator for FrozenModulesIter {
+        type Item = (String, FrozenModule);
+
+        fn next(&mut self) -> Option<Self::Item> {
+            // manually mimic bincode's seq encoding, which is <len:u64> <element*len>
+            // This probably won't change (bincode doesn't require padding or anything), but
+            // it's not guaranteed by semver as far as I can tell
+            if self.len > 0 {
+                let entry = Deserialize::deserialize(&mut self.de).unwrap();
+                self.len -= 1;
+                Some(entry)
+            } else {
+                None
+            }
+        }
+
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            (self.len, Some(self.len))
+        }
+    }
+
+    impl ExactSizeIterator for FrozenModulesIter {}
+
+    pub fn encode_lib<'a, I>(lib: I) -> Vec<u8>
+    where
+        I: IntoIterator<Item = (&'a str, &'a FrozenModule)>,
+        I::IntoIter: ExactSizeIterator + Clone,
+    {
+        let iter = lib.into_iter();
+        let data = options().serialize(&SerializeLib { iter }).unwrap();
+        lz4_flex::compress_prepend_size(&data)
+    }
+
+    struct SerializeLib<I> {
+        iter: I,
+    }
+
+    impl<'a, I> Serialize for SerializeLib<I>
+    where
+        I: ExactSizeIterator<Item = (&'a str, &'a FrozenModule)> + Clone,
+    {
+        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+        where
+            S: serde::Serializer,
+        {
+            serializer.collect_seq(self.iter.clone())
+        }
+    }
+
+    /// Owned version of bincode::de::read::SliceReader<'a>
+    struct VecReader {
+        data: Vec<u8>,
+        pos: usize,
+    }
+
+    impl io::Read for VecReader {
+        fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+            let mut subslice = &self.data[self.pos..];
+            let n = io::Read::read(&mut subslice, buf)?;
+            self.pos += n;
+            Ok(n)
+        }
+        fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
+            self.get_byte_slice(buf.len())
+                .map(|data| buf.copy_from_slice(data))
+        }
+    }
+
+    impl VecReader {
+        #[inline(always)]
+        fn get_byte_slice(&mut self, length: usize) -> io::Result<&[u8]> {
+            let subslice = &self.data[self.pos..];
+            match subslice.get(..length) {
+                Some(ret) => {
+                    self.pos += length;
+                    Ok(ret)
+                }
+                None => Err(io::ErrorKind::UnexpectedEof.into()),
+            }
+        }
+    }
+
+    impl<'storage> bincode::BincodeRead<'storage> for VecReader {
+        fn forward_read_str<V>(&mut self, length: usize, visitor: V) -> bincode::Result<V::Value>
+        where
+            V: serde::de::Visitor<'storage>,
+        {
+            let bytes = self.get_byte_slice(length)?;
+            match ::std::str::from_utf8(bytes) {
+                Ok(s) => visitor.visit_str(s),
+                Err(e) => Err(bincode::ErrorKind::InvalidUtf8Encoding(e).into()),
+            }
+        }
+
+        fn get_byte_buffer(&mut self, length: usize) -> bincode::Result<Vec<u8>> {
+            self.get_byte_slice(length)
+                .map(|x| x.to_vec())
+                .map_err(Into::into)
+        }
+
+        fn forward_read_bytes<V>(&mut self, length: usize, visitor: V) -> bincode::Result<V::Value>
+        where
+            V: serde::de::Visitor<'storage>,
+        {
+            visitor.visit_bytes(self.get_byte_slice(length)?)
+        }
+    }
+}
diff --git a/derive/src/compile_bytecode.rs b/derive/src/compile_bytecode.rs
index 852df198a3..bca2e76213 100644
--- a/derive/src/compile_bytecode.rs
+++ b/derive/src/compile_bytecode.rs
@@ -330,30 +330,11 @@ pub fn impl_py_freeze(input: TokenStream2) -> Result<TokenStream2, Diagnostic> {
     let crate_name = args.crate_name;
     let code_map = args.source.compile(args.mode, args.module_name)?;
 
-    let modules_len = code_map.len();
-
-    let modules = code_map
-        .into_iter()
-        .map(|(module_name, FrozenModule { code, package })| {
-            let module_name = LitStr::new(&module_name, Span::call_site());
-            let bytes = code.to_bytes();
-            let bytes = LitByteStr::new(&bytes, Span::call_site());
-            quote! {
-                m.insert(#module_name.into(), #crate_name::FrozenModule {
-                    code: #crate_name::CodeObject::from_bytes(
-                        #bytes
-                    ).expect("Deserializing CodeObject failed"),
-                    package: #package,
-                });
-            }
-        });
+    let data = rustpython_bytecode::frozen_lib::encode_lib(code_map.iter().map(|(k, v)| (&**k, v)));
+    let bytes = LitByteStr::new(&data, Span::call_site());
 
     let output = quote! {
-        {
-            let mut m = ::std::collections::HashMap::with_capacity(#modules_len);
-            #(#modules)*
-            m
-        }
+        #crate_name::frozen_lib::decode_lib(#bytes)
     };
 
     Ok(output)
diff --git a/examples/freeze/main.rs b/examples/freeze/main.rs
index d9cc11778c..b406296bac 100644
--- a/examples/freeze/main.rs
+++ b/examples/freeze/main.rs
@@ -1,5 +1,3 @@
-use std::collections::HashMap;
-
 use rustpython_vm as vm;
 
 fn main() -> vm::pyobject::PyResult<()> {
@@ -11,13 +9,9 @@ fn run(vm: &vm::VirtualMachine) -> vm::pyobject::PyResult<()> {
 
     // the file parameter is relevant to the directory where the crate's Cargo.toml is located, see $CARGO_MANIFEST_DIR:
     // https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates
-    let modules: HashMap<String, vm::bytecode::FrozenModule> =
-        vm::py_freeze!(file = "examples/freeze/freeze.py");
+    let module = vm::py_compile!(file = "examples/freeze/freeze.py");
 
-    let res = vm.run_code_obj(
-        vm.new_code_object(modules.get("frozen").unwrap().code.clone()),
-        scope,
-    );
+    let res = vm.run_code_obj(vm.new_code_object(module), scope);
 
     if let Err(err) = res {
         vm::exceptions::print_exception(&vm, err);
diff --git a/vm/pylib-crate/src/lib.rs b/vm/pylib-crate/src/lib.rs
index 895654c57b..d53aabe2f1 100644
--- a/vm/pylib-crate/src/lib.rs
+++ b/vm/pylib-crate/src/lib.rs
@@ -5,8 +5,8 @@
 pub const LIB_PATH: &str = concat!(env!("CARGO_MANIFEST_DIR"), "/Lib");
 
 #[cfg(feature = "compiled-bytecode")]
-use {rustpython_bytecode::FrozenModule, std::collections::HashMap};
+use rustpython_bytecode::FrozenModule;
 #[cfg(feature = "compiled-bytecode")]
-pub fn frozen_stdlib() -> HashMap<String, FrozenModule> {
+pub fn frozen_stdlib() -> impl Iterator<Item = (String, FrozenModule)> {
     rustpython_derive::py_freeze!(dir = "Lib", crate_name = "rustpython_bytecode")
 }
diff --git a/vm/src/frozen.rs b/vm/src/frozen.rs
index d98d9c9187..ec94b7ecdb 100644
--- a/vm/src/frozen.rs
+++ b/vm/src/frozen.rs
@@ -1,7 +1,6 @@
 use crate::builtins::code;
 use crate::bytecode;
 use crate::VirtualMachine;
-use std::collections::HashMap;
 
 pub fn map_frozen<'a>(
     vm: &'a VirtualMachine,
@@ -19,18 +18,19 @@ pub fn map_frozen<'a>(
         })
 }
 
-pub fn get_module_inits(
-    vm: &VirtualMachine,
-) -> HashMap<String, code::FrozenModule, ahash::RandomState> {
-    let mut modules = HashMap::default();
-
+pub fn get_module_inits() -> impl Iterator<Item = (String, bytecode::FrozenModule)> {
+    let iter = std::iter::empty();
     macro_rules! ext_modules {
-        ($($t:tt)*) => {
-            modules.extend(map_frozen(vm, py_freeze!($($t)*)));
+        ($iter:ident, ($modules:expr)) => {
+            let $iter = $iter.chain($modules);
+        };
+        ($iter:ident, $($t:tt)*) => {
+            ext_modules!($iter, (py_freeze!($($t)*)))
         };
     }
 
     ext_modules!(
+        iter,
         source = "initialized = True; print(\"Hello world!\")\n",
         module_name = "__hello__",
     );
@@ -39,19 +39,15 @@ pub fn get_module_inits(
     // in theory be implemented in Rust, but are easiest to do in Python for one reason or another.
     // Includes _importlib_bootstrap and _importlib_bootstrap_external
     // For Windows: did you forget to run `powershell scripts\symlinks-to-hardlinks.ps1`?
-    ext_modules!(dir = "Lib/python_builtins/");
+    ext_modules!(iter, dir = "Lib/python_builtins/");
 
     #[cfg(not(feature = "freeze-stdlib"))]
-    {
-        // core stdlib Python modules that the vm calls into, but are still used in Python
-        // application code, e.g. copyreg
-        ext_modules!(dir = "Lib/core_modules/");
-    }
+    // core stdlib Python modules that the vm calls into, but are still used in Python
+    // application code, e.g. copyreg
+    ext_modules!(iter, dir = "Lib/core_modules/");
     // if we're on freeze-stdlib, the core stdlib modules will be included anyway
     #[cfg(feature = "freeze-stdlib")]
-    {
-        modules.extend(map_frozen(vm, rustpython_pylib::frozen_stdlib()));
-    }
+    ext_modules!(iter, (rustpython_pylib::frozen_stdlib()));
 
-    modules
+    iter
 }
diff --git a/vm/src/vm.rs b/vm/src/vm.rs
index 77e51b3cf3..8980b80c7c 100644
--- a/vm/src/vm.rs
+++ b/vm/src/vm.rs
@@ -282,7 +282,7 @@ impl VirtualMachine {
             initialized: false,
         };
 
-        let frozen = frozen::get_module_inits(&vm);
+        let frozen = frozen::map_frozen(&vm, frozen::get_module_inits()).collect();
         PyRc::get_mut(&mut vm.state).unwrap().frozen = frozen;
 
         module::init_module_dict(