3 files changed, 42 insertions, 3 deletions
diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 11110a78f..f9214c999 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -32,6 +32,7 @@ deno_core = { workspace = true, features = ["include_js_files_for_snapshotting"]
 regex.workspace = true
 serde.workspace = true
 serde_json.workspace = true
+zstd.workspace = true
 glibc_version = "0.1.2"
 
 [target.'cfg(windows)'.build-dependencies]
@@ -105,6 +106,7 @@ twox-hash = "=1.6.3"
 typed-arena = "=2.0.1"
 uuid = { workspace = true, features = ["serde"] }
 walkdir = "=2.3.2"
+zstd.workspace = true
 
 [target.'cfg(windows)'.dependencies]
 fwdansi.workspace = true
diff --git a/cli/build.rs b/cli/build.rs
index 251b30de2..ecd7ed1be 100644
--- a/cli/build.rs
+++ b/cli/build.rs
@@ -270,7 +270,22 @@ mod ts {
         build_libs,
         path_dts,
       )],
+
+      // NOTE(bartlomieju): Compressing the TSC snapshot in debug build took
+      // ~45s on M1 MacBook Pro; without compression it took ~1s.
+      // Thus we're not not using compressed snapshot, trading off
+      // a lot of build time for some startup time in debug build.
+      #[cfg(debug_assertions)]
       compression_cb: None,
+
+      #[cfg(not(debug_assertions))]
+      compression_cb: Some(Box::new(|vec, snapshot_slice| {
+        eprintln!("Compressing TSC snapshot...");
+        vec.extend_from_slice(
+          &zstd::bulk::compress(snapshot_slice, 22)
+            .expect("snapshot compression failed"),
+        );
+      })),
       snapshot_module_load_cb: None,
     });
   }
diff --git a/cli/tsc/mod.rs b/cli/tsc/mod.rs
index 60ef1c5d6..43fccb37e 100644
--- a/cli/tsc/mod.rs
+++ b/cli/tsc/mod.rs
@@ -52,8 +52,30 @@ pub use self::diagnostics::DiagnosticMessageChain;
 pub use self::diagnostics::Diagnostics;
 pub use self::diagnostics::Position;
 
-pub static COMPILER_SNAPSHOT: &[u8] =
-  include_bytes!(concat!(env!("OUT_DIR"), "/COMPILER_SNAPSHOT.bin"));
+pub static COMPILER_SNAPSHOT: Lazy<Box<[u8]>> = Lazy::new(
+  #[cold]
+  #[inline(never)]
+  || {
+    static COMPRESSED_COMPILER_SNAPSHOT: &[u8] =
+      include_bytes!(concat!(env!("OUT_DIR"), "/COMPILER_SNAPSHOT.bin"));
+
+    // NOTE(bartlomieju): Compressing the TSC snapshot in debug build took
+    // ~45s on M1 MacBook Pro; without compression it took ~1s.
+    // Thus we're not not using compressed snapshot, trading off
+    // a lot of build time for some startup time in debug build.
+    #[cfg(debug_assertions)]
+    return COMPRESSED_COMPILER_SNAPSHOT.to_vec().into_boxed_slice();
+
+    #[cfg(not(debug_assertions))]
+    zstd::bulk::decompress(
+      &COMPRESSED_COMPILER_SNAPSHOT[4..],
+      u32::from_le_bytes(COMPRESSED_COMPILER_SNAPSHOT[0..4].try_into().unwrap())
+        as usize,
+    )
+    .unwrap()
+    .into_boxed_slice()
+  },
+);
 
 pub fn get_types_declaration_file_text(unstable: bool) -> String {
   let mut assets = get_asset_texts_from_new_runtime()
@@ -115,7 +137,7 @@ fn get_asset_texts_from_new_runtime() -> Result<Vec<AssetText>, AnyError> {
 }
 
 pub fn compiler_snapshot() -> Snapshot {
-  Snapshot::Static(COMPILER_SNAPSHOT)
+  Snapshot::Static(&COMPILER_SNAPSHOT)
 }
 
 macro_rules! inc {