diff --git a/imperative/python/megengine/core/tensor/utils.py b/imperative/python/megengine/core/tensor/utils.py
index a3d764021b6b7b02ad78f4cee77fe60f4d840358..a0e2648eb354edba5e9f20ec4c567f12ee8e83fb 100644
--- a/imperative/python/megengine/core/tensor/utils.py
+++ b/imperative/python/megengine/core/tensor/utils.py
@@ -22,6 +22,7 @@ from .._imperative_rt.core2 import (
     make_shape_tuple,
 )
 from .._imperative_rt.ops import SubgraphBuilder as _SubgraphBuilder
+from .._imperative_rt.ops import jit_supported
 from .._wrap import as_device
 from ..autodiff.grad import Function
 from ..ops import builtin
@@ -234,6 +235,10 @@ def subgraph(
         gopt_level = None  # disable jit and compile
         jit_fusion = False
 
+    if jit_fusion and not jit_supported:
+        jit_fusion = False  # jit unusable, fallback to graph compile
+        gopt_level = 2
+
     def as_op(op, nargs):
         if isinstance(op, str):
             assert (op, nargs) in _opr_map, "unknown operator"
diff --git a/imperative/python/src/ops.cpp b/imperative/python/src/ops.cpp
index aea124e16cc0f62f46d17246ddeaa603eb83d231..3bc859aac746ee74701165931d60fba56ebeb1a7 100644
--- a/imperative/python/src/ops.cpp
+++ b/imperative/python/src/ops.cpp
@@ -652,6 +652,11 @@ void init_ops(py::module m) {
             });
 
     m.def("set_jit_enabled", &JITFusionOp::set_enabled);
+    bool jit_supported = false;
+#if MGB_JIT
+    jit_supported = true;
+#endif
+    m.attr("jit_supported") = jit_supported;
 
     auto custom = submodule(m, "_custom");
     init_custom(custom);
diff --git a/imperative/src/impl/ops/utility.cpp b/imperative/src/impl/ops/utility.cpp
index 07a434a3ffcc2af61df917d86a02c3b6be402d2b..8ac834f249c54fdb89bdab9aab5094ce3c33015a 100644
--- a/imperative/src/impl/ops/utility.cpp
+++ b/imperative/src/impl/ops/utility.cpp
@@ -9,21 +9,26 @@
  * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  */
 
-#include <queue>
+#include <deque>
 
-#include "../op_trait.h"
 #include "megbrain/imperative/graph_cache.h"
 #include "megbrain/imperative/opr_utility.h"
 #include "megbrain/imperative/ops/autogen.h"
 #include "megbrain/imperative/ops/opr_attr.h"
 #include "megbrain/imperative/ops/utility.h"
 #include "megbrain/imperative/subgraph_detail.h"
-#include "megbrain/jit/executor_opr.h"
 #include "megbrain/opr/io.h"
 #include "megbrain/opr/tensor_gen.h"
 #include "megbrain/opr/tensor_manip.h"
 #include "megbrain/opr/utility.h"
 
+#if MGB_JIT
+#include "megbrain/jit/executor_opr.h"
+#endif
+
+#include "../event_pool.h"
+#include "../op_trait.h"
+
 namespace mgb::imperative {
 
 MGB_DYN_TYPE_OBJ_FINAL_IMPL(GenericPyOp);
@@ -309,7 +314,7 @@ struct ComputingGraphHolder {
     SmallVector<VarNode*> input_vars;
     SmallVector<VarNode*> output_vars;
     std::shared_ptr<DeviceMemoryAllocatorImpl> allocator;
-    SmallVector<std::unique_ptr<CompNode::Event>> events;
+    SmallVector<std::shared_ptr<CompNode::Event>> events;
     std::unique_ptr<cg::static_infer::StaticInferUpdater> updater;
 
     void initialize(
@@ -402,7 +407,7 @@ struct ComputingGraphHolder {
             return true;
         });
         for (auto&& comp_node : comp_nodes) {
-            events.push_back(comp_node.create_event());
+            events.push_back(EventPool::without_timer().alloc_shared(comp_node));
             events.back()->record();
         }
     }
@@ -510,7 +515,7 @@ ComputingGraphHolder<Kind>& get_computing_graph(
         std::shared_ptr<OpDef> compiled_op,
         const SmallVector<LogicalTensorDesc>& descs) {
     using ComputingGraphHolderCache =
-            OpMethResultCache<std::queue<std::unique_ptr<ComputingGraphHolder<Kind>>>>;
+            OpMethResultCache<std::deque<std::unique_ptr<ComputingGraphHolder<Kind>>>>;
     thread_local auto cache = std::make_unique<ComputingGraphHolderCache>();
     thread_local size_t nr_cg_holders = 0;
     typename ComputingGraphHolderCache::key_t cache_key = {compiled_op, descs};
@@ -540,20 +545,28 @@ ComputingGraphHolder<Kind>& get_computing_graph(
             }
         }
         if (holder) {
-            cg_holder_queue.pop();
+            cg_holder_queue.pop_front();
         }
     }
     if (!holder) {
         // create new computing graph
-        holder = std::make_unique<ComputingGraphHolder<Kind>>();
-        auto& cg_holder = *holder;
-        cg_holder.initialize(compiled_op->cast_final_safe<CompiledOp>(), descs);
-        nr_cg_holders++;
-        mgb_log_debug(
-                "add new computing graph for compiled op, now %zu graphs",
-                nr_cg_holders);
+        auto create_holder = [&] {
+            auto holder = std::make_unique<ComputingGraphHolder<Kind>>();
+            auto& cg_holder = *holder;
+            cg_holder.initialize(compiled_op->cast_final_safe<CompiledOp>(), descs);
+            nr_cg_holders++;
+            mgb_log_debug(
+                    "add new computing graph for compiled op, now %zu graphs",
+                    nr_cg_holders);
+            return holder;
+        };
+        size_t nr_graphs = std::max(cg_holder_queue.size(), (size_t)1);
+        for (size_t i = 1; i < nr_graphs; ++i) {
+            cg_holder_queue.push_front(create_holder());
+        }
+        holder = create_holder();
     }
-    cg_holder_queue.push(std::move(holder));
+    cg_holder_queue.push_back(std::move(holder));
     return *cg_holder_queue.back();
 }
 
@@ -670,6 +683,7 @@ auto apply_on_var_node(const OpDef& def, const VarNodeArray& inputs) {
         // skip for dump (JITExecutor can not be dumped)
         return outputs;
     }
+#if MGB_JIT
     for (auto& output : outputs) {
         jit::InternalGraphGenerator igg{output->owner_opr()};
         std::vector<cg::OperatorNodeBase*> reverse_order;
@@ -686,6 +700,9 @@ auto apply_on_var_node(const OpDef& def, const VarNodeArray& inputs) {
         auto ig = igg.generate();
         output = jit::JITExecutor::make(ig, igg.orig_inps()).node();
     }
+#else
+    mgb_assert(false, "MGB_WITH_JIT was disabled");
+#endif
     return outputs;
 }
 
diff --git a/src/jit/impl/nvrtc/compiler_cuda.cpp b/src/jit/impl/nvrtc/compiler_cuda.cpp
index df5d8399b80989d08ca78f1d457c26d699f50c44..cc600f45abe1799ed7363ff4995f181496ff690f 100644
--- a/src/jit/impl/nvrtc/compiler_cuda.cpp
+++ b/src/jit/impl/nvrtc/compiler_cuda.cpp
@@ -216,11 +216,11 @@ void CudaExecutable::FuncCache::compile(
         ptx = NVRTCCompile(cuda_exe->m_source, major, minor);
         ptx_cache = PersistentCache::Blob{ptx.data(), ptx.size()};
         cache.put(cache_category, key, ptx_cache.val());
+        mgb_log("NVRTC JIT: compile %s for %d.%d: source_len=%zu ptx_len=%zu "
+                "time=%.3fms",
+                cuda_exe->m_name.c_str(), major, minor, key.size, ptx.size(),
+                timer.get_msecs());
     }
-    mgb_log("NVRTC JIT: compile %s for %d.%d: source_len=%zu ptx_len=%zu "
-            "time=%.3fms",
-            cuda_exe->m_name.c_str(), major, minor, key.size, ptx.size(),
-            timer.get_msecs());
 }
 
 void CudaExecutable::FuncCache::exec(