feat(sdk): enhance dev mode warning with opt-level detection

- Add opt-level detection in build script
- Set environment variable when optimization level is low
- Update warning message to be more visible with clear instructions
- Replace debug_assertions check with opt-level detection

Co-Authored-By: [email protected] <[email protected]>

crates/sdk/build.rs

@@ -1,3 +1,8 @@
 fn main() {
     vergen::EmitBuilder::builder().build_timestamp().git_sha(true).emit().unwrap();
+
+    let opt_level = std::env::var("OPT_LEVEL").unwrap_or_else(|_| "0".to_string());
+    if opt_level == "0" || opt_level == "1" {
+        println!("cargo:rustc-env=SP1_OPT_LEVEL_IS_LOW=1");
+    }
 }

crates/sdk/src/lib.rs

@@ -76,8 +76,15 @@ impl ProverClient {
         match env::var("SP1_PROVER").unwrap_or("local".to_string()).to_lowercase().as_str() {
             "mock" => Self { prover: Box::new(MockProver::new()) },
             "local" => {
-                #[cfg(debug_assertions)]
-                eprintln!("Warning: Local prover in dev mode is not recommended. Proof generation may be slow.");
+                if option_env!("SP1_OPT_LEVEL_IS_LOW").is_some() {
+                    eprintln!("\n⚠️  WARNING: Local prover is running with low optimization level (dev mode) ⚠️");
+                    eprintln!("This will significantly impact proof generation performance.");
+                    eprintln!("To improve performance, either:");
+                    eprintln!("  1. Use --release flag when running cargo");
+                    eprintln!("  2. Add the following to Cargo.toml:");
+                    eprintln!("     [profile.dev.package.\"*\"]");
+                    eprintln!("     opt-level = 3\n");
+                }
                 Self {
                     #[cfg(not(feature = "cuda"))]
                     prover: Box::new(CpuProver::new()),