diff --git a/bench_util/benches/op_baseline.rs b/bench_util/benches/op_baseline.rs
index 317be79829..14d04f60d0 100644
--- a/bench_util/benches/op_baseline.rs
+++ b/bench_util/benches/op_baseline.rs
@@ -41,16 +41,6 @@ fn bench_op_async(b: &mut Bencher) {
   bench_js_async(b, r#"Deno.core.opAsync("op_pi_async");"#, setup);
 }
 
-fn bench_is_proxy(b: &mut Bencher) {
-  bench_js_sync(b, r#"Deno.core.isProxy(42);"#, setup);
-}
-
-benchmark_group!(
-  benches,
-  bench_op_pi_json,
-  bench_op_nop,
-  bench_op_async,
-  bench_is_proxy
-);
+benchmark_group!(benches, bench_op_pi_json, bench_op_nop, bench_op_async,);
 
 bench_or_profile!(benches);
diff --git a/core/01_core.js b/core/01_core.js
index e1ac275ebf..c7ced9b82e 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -306,7 +306,7 @@
     deserialize: (buffer, options) => ops.op_deserialize(buffer, options),
     getPromiseDetails: (promise) => ops.op_get_promise_details(promise),
     getProxyDetails: (proxy) => ops.op_get_proxy_details(proxy),
-    isProxy: (value) => ops.op_is_proxy(value),
+    isProxy: (value) => ops.op_is_proxy.fast(value),
     memoryUsage: () => ops.op_memory_usage(),
     setWasmStreamingCallback: (fn) => ops.op_set_wasm_streaming_callback(fn),
     abortWasmStreaming: (
diff --git a/core/ops_builtin.rs b/core/ops_builtin.rs
index 2e911e4150..bd19b74f6b 100644
--- a/core/ops_builtin.rs
+++ b/core/ops_builtin.rs
@@ -191,7 +191,7 @@ fn op_format_file_name(file_name: String) -> String {
   format_file_name(&file_name)
 }
 
-#[op]
+#[op(fast)]
 fn op_is_proxy(value: serde_v8::Value) -> bool {
   value.v8_value.is_proxy()
 }
diff --git a/core/runtime.rs b/core/runtime.rs
index 50c108f33f..366e834a26 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -3121,6 +3121,7 @@ assertEquals(1, notify_return_value);
     runtime.execute_script("<none>", "").unwrap();
   }
 
+  #[ignore] // TODO(@littledivy): Fast API ops when snapshot is not loaded.
   #[test]
   fn test_is_proxy() {
     let mut runtime = JsRuntime::new(RuntimeOptions::default());
diff --git a/ops/lib.rs b/ops/lib.rs
index 0b0689356b..7d291d1da5 100644
--- a/ops/lib.rs
+++ b/ops/lib.rs
@@ -304,6 +304,7 @@ fn codegen_fast_impl(
       args,
       ret,
       use_recv,
+      v8_values,
     }) = fast_info
     {
       let inputs = &f
@@ -311,17 +312,42 @@ fn codegen_fast_impl(
         .inputs
         .iter()
         .skip(if use_recv { 1 } else { 0 })
+        .enumerate()
+        .map(|(idx, arg)| {
+          if v8_values.contains(&idx) {
+            let ident = match arg {
+              FnArg::Receiver(_) => unreachable!(),
+              FnArg::Typed(t) => match &*t.pat {
+                syn::Pat::Ident(i) => format_ident!("{}", i.ident),
+                _ => unreachable!(),
+              },
+            };
+            return quote! { #ident: #core::v8::Local < #core::v8::Value > };
+          }
+          quote!(#arg)
+        })
         .collect::<Vec<_>>();
       let input_idents = f
         .sig
         .inputs
         .iter()
-        .map(|a| match a {
-          FnArg::Receiver(_) => unreachable!(),
-          FnArg::Typed(t) => match &*t.pat {
-            syn::Pat::Ident(i) => format_ident!("{}", i.ident),
-            _ => unreachable!(),
-          },
+        .enumerate()
+        .map(|(idx, a)| {
+          let ident = match a {
+            FnArg::Receiver(_) => unreachable!(),
+            FnArg::Typed(t) => match &*t.pat {
+              syn::Pat::Ident(i) => format_ident!("{}", i.ident),
+              _ => unreachable!(),
+            },
+          };
+          if v8_values.contains(&idx) {
+            return quote! {
+              #core::serde_v8::Value {
+                v8_value: #ident,
+              }
+            };
+          }
+          quote! { #ident }
         })
         .collect::<Vec<_>>();
       let generics = &f.sig.generics;
@@ -453,6 +479,7 @@ struct FastApiSyn {
   args: TokenStream2,
   ret: TokenStream2,
   use_recv: bool,
+  v8_values: Vec<usize>,
 }
 
 fn can_be_fast_api(core: &TokenStream2, f: &syn::ItemFn) -> Option<FastApiSyn> {
@@ -466,6 +493,7 @@ fn can_be_fast_api(core: &TokenStream2, f: &syn::ItemFn) -> Option<FastApiSyn> {
   };
 
   let mut use_recv = false;
+  let mut v8_values = Vec::new();
   let mut args = vec![quote! { #core::v8::fast_api::Type::V8Value }];
   for (pos, input) in inputs.iter().enumerate() {
     if pos == 0 && is_mut_ref_opstate(input) {
@@ -478,16 +506,21 @@ fn can_be_fast_api(core: &TokenStream2, f: &syn::ItemFn) -> Option<FastApiSyn> {
       _ => unreachable!(),
     };
 
-    match is_fast_scalar(core, ty, false) {
-      None => match is_fast_arg_sequence(core, ty) {
+    if let Some(arg) = is_fast_v8_value(core, ty) {
+      args.push(arg);
+      v8_values.push(pos);
+    } else {
+      match is_fast_scalar(core, ty, false) {
+        None => match is_fast_arg_sequence(core, ty) {
+          Some(arg) => {
+            args.push(arg);
+          }
+          // early return, this function cannot be a fast call.
+          None => return None,
+        },
         Some(arg) => {
           args.push(arg);
         }
-        // early return, this function cannot be a fast call.
-        None => return None,
-      },
-      Some(arg) => {
-        args.push(arg);
       }
     }
   }
@@ -501,6 +534,7 @@ fn can_be_fast_api(core: &TokenStream2, f: &syn::ItemFn) -> Option<FastApiSyn> {
     args: args.parse().unwrap(),
     ret,
     use_recv,
+    v8_values,
   })
 }
 
@@ -523,6 +557,16 @@ fn is_fast_arg_sequence(
   None
 }
 
+fn is_fast_v8_value(
+  core: &TokenStream2,
+  arg: impl ToTokens,
+) -> Option<TokenStream2> {
+  if tokens(&arg).contains("serde_v8 :: Value") {
+    return Some(quote! { #core::v8::fast_api::Type::V8Value });
+  }
+  None
+}
+
 fn is_local_array(arg: impl ToTokens) -> bool {
   static RE: Lazy<Regex> =
     Lazy::new(|| Regex::new(r"^v8::Local<v8::Array>$").unwrap());
@@ -558,6 +602,7 @@ fn is_fast_scalar(
     "i32" => Some(quote! { #core::v8::fast_api::#cty::Int32 }),
     "f32" => Some(quote! { #core::v8::fast_api::#cty::Float32 }),
     "f64" => Some(quote! { #core::v8::fast_api::#cty::Float64 }),
+    "bool" => Some(quote! { #core::v8::fast_api::#cty::Bool }),
     _ => None,
   }
 }