diff --git a/setup.py b/setup.py
index 7f95bf093..7fd343759 100644
--- a/setup.py
+++ b/setup.py
@@ -496,6 +496,35 @@ def _env_enabled_any(names, default="1") -> bool:
         cpp_ext = None
 
     if cpp_ext is not None:
+        # Limit compile parallelism to avoid overwhelming nvcc/cicc invocations.
+        # Respect pre-set MAX_JOBS, otherwise fall back to CPU count minus two (min 1).
+        cpu_count = os.cpu_count() or 1
+        default_max_jobs = max(1, cpu_count - 2)
+        max_jobs_raw = os.environ.get("MAX_JOBS")
+        if max_jobs_raw is None or max_jobs_raw.strip() == "":
+            effective_max_jobs = default_max_jobs
+            print(f"MAX_JOBS not set; defaulting to {effective_max_jobs} concurrent CUDA compilations.")
+        else:
+            try:
+                parsed_jobs = int(max_jobs_raw)
+            except ValueError:
+                effective_max_jobs = default_max_jobs
+                print(f"Ignoring invalid MAX_JOBS={max_jobs_raw!r}; using {effective_max_jobs}.")
+            else:
+                if parsed_jobs <= 0:
+                    effective_max_jobs = default_max_jobs
+                    print(f"MAX_JOBS={parsed_jobs} is non-positive; using {effective_max_jobs}.")
+                else:
+                    effective_max_jobs = parsed_jobs
+
+        os.environ["MAX_JOBS"] = str(effective_max_jobs)
+        os.environ["NINJA_NUM_JOBS"] = str(effective_max_jobs)
+        print(f"Using MAX_JOBS={effective_max_jobs} to cap concurrent CUDA compilations.")
+
+        nvcc_threads = 1
+        os.environ["NVCC_THREADS"] = str(nvcc_threads)
+        print(f"Using NVCC_THREADS={nvcc_threads} for per-invocation NVCC concurrency.")
+
         # Optional conda CUDA runtime headers
         #conda_cuda_include_dir = os.path.join(get_python_lib(), "nvidia/cuda_runtime/include")
         # if os.path.isdir(conda_cuda_include_dir):
@@ -543,7 +572,7 @@ def _env_enabled_any(names, default="1") -> bool:
             # if _version_geq(NVCC_VERSION, 13, 0):
             #     extra_compile_args["nvcc"].append("--device-entity-has-hidden-visibility=false")
             nvcc_extra_flags = [
-                "--threads", "8",  # NVCC parallelism
+                "--threads", str(nvcc_threads),  # NVCC parallelism
                 "--optimize=3",  # alias for -O3
                 # "-rdc=true",  # enable relocatable device code, required for future cuda > 13.x <-- TODO FIX ME broken loading
                 # "-dlto",      # compile and link <-- TODO FIX ME