diff --git a/prover/src/test_utils.rs b/prover/src/test_utils.rs
index d6a8b8608..3c17b2848 100644
--- a/prover/src/test_utils.rs
+++ b/prover/src/test_utils.rs
@@ -671,6 +671,12 @@ fn build_air<CS: ConstraintSet<F, E> + Clone + Send + Sync + 'static>(
     .with_name(name);
     // Pre-capture the constraint IR so every clone carries it (the prover's
     // GPU lowering and interpreter paths force it per instance otherwise).
+    //
+    // NOT on the guest: the in-VM verifier reaches `build_air` through
+    // `VmAirs::new` and never calls `constraint_program()`, so capturing here
+    // buys it nothing and costs a full IR build per AIR — measured as ~9.7% of
+    // the recursion guest's cycles on a real block.
+    #[cfg(not(target_arch = "riscv64"))]
     let _ = air.constraint_program();
     air_prototype_cache()
         .lock()