diff --git a/backends/tfhe-cuda-backend/cuda/src/fft/bnsmfft.cuh b/backends/tfhe-cuda-backend/cuda/src/fft/bnsmfft.cuh
index a57dd0d0c9..f6cc6ba044 100644
--- a/backends/tfhe-cuda-backend/cuda/src/fft/bnsmfft.cuh
+++ b/backends/tfhe-cuda-backend/cuda/src/fft/bnsmfft.cuh
@@ -715,4 +715,312 @@ __global__ void batch_polynomial_mul(double2 *d_input1, double2 *d_input2,
   }
 }
 
+template <class params> __device__ void NSMFFT_direct_bundle(double2 *A, const double2 regs[4]) {
+
+  /* We don't make bit reverse here, since twiddles are already reversed
+   *  Each thread is always in charge of "opt/2" pairs of coefficients,
+   *  which is why we always loop through N/2 by N/opt strides
+   *  The pragma unroll instruction tells the compiler to unroll the
+   *  full loop, which should increase performance
+   */
+
+  size_t tid = threadIdx.x;
+  size_t twid_id;
+  size_t i1, i2;
+  double2 u, v, w;
+  // level 1
+  // we don't make actual complex multiplication on level1 since we have only
+  // one twiddle, it's real and image parts are equal, so we can multiply
+  // it with simpler operations
+  // degree = 1024, opt = 2 -> 
+#pragma unroll
+  for (size_t i = 0; i < params::opt / 2; ++i) {
+    i1 = tid;
+    i2 = tid + params::degree / 2;
+
+    //u = A[i1];
+    //v = A[i2] * (double2){0.707106781186547461715008466854,
+    //                      0.707106781186547461715008466854};
+
+    u = regs[i];
+    v = regs[i + params::opt / 2] * (double2){0.707106781186547461715008466854,
+                          0.707106781186547461715008466854};
+    //A[i1] += v;
+    A[i1] = u + v;
+    A[i2] = u - v;
+
+    tid += params::degree / params::opt; //256
+  }
+  
+  __syncthreads();
+
+  // level 2
+  // from this level there are more than one twiddles and none of them has equal
+  // real and imag parts, so complete complex multiplication is needed
+  // for each level params::degree / 2^level represents number of coefficients
+  // inside divided chunk of specific level
+  //
+#pragma unroll
+  for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+    tid = threadIdx.x + i * params::degree / params::opt;
+    twid_id = tid / (params::degree / 4);
+    i1 = 2 * (params::degree / 4) * twid_id + (tid & (params::degree / 4 - 1));
+    i2 = i1 + params::degree / 4;
+
+    w = negtwiddles[twid_id + 2];
+    u = A[i1];
+    v = A[i2] * w;
+  
+    A[i1] += v;
+    A[i2] = u - v;
+  }
+  __syncthreads();
+
+  // level 3
+  tid = threadIdx.x;
+#pragma unroll
+  for (size_t i = 0; i < params::opt / 2; ++i) {
+    twid_id = tid / (params::degree / 8);
+    i1 = 2 * (params::degree / 8) * twid_id + (tid & (params::degree / 8 - 1));
+    i2 = i1 + params::degree / 8;
+
+    w = negtwiddles[twid_id + 4];
+    u = A[i1];
+    v = A[i2] * w;
+
+    A[i1] += v;
+    A[i2] = u - v;
+
+    tid += params::degree / params::opt;
+  }
+  __syncthreads();
+
+  // level 4
+  //tid = threadIdx.x;
+  //for (size_t i = 0; i < params::opt / 2; ++i) {
+#pragma unroll
+  for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+    tid = threadIdx.x + i * params::degree / params::opt;
+    twid_id = tid / (params::degree / 16);
+    i1 =
+        2 * (params::degree / 16) * twid_id + (tid & (params::degree / 16 - 1));
+    i2 = i1 + params::degree / 16;
+
+    w = negtwiddles[twid_id + 8];
+    u = A[i1];
+    v = A[i2] * w;
+
+    A[i1] += v;
+    A[i2] = u - v;
+
+    //tid += params::degree / params::opt;
+  }
+  __syncthreads();
+
+  // level 5
+  tid = threadIdx.x;
+#pragma unroll
+  for (size_t i = 0; i < params::opt / 2; ++i) {
+    twid_id = tid / (params::degree / 32);
+    i1 =
+        2 * (params::degree / 32) * twid_id + (tid & (params::degree / 32 - 1));
+    i2 = i1 + params::degree / 32;
+
+    w = negtwiddles[twid_id + 16];
+    u = A[i1];
+    v = A[i2] * w;
+
+    A[i1] += v;
+    A[i2] = u - v;
+
+    tid += params::degree / params::opt;
+  }
+  __syncthreads();
+
+  // level 6
+  //tid = threadIdx.x;
+  //for (size_t i = 0; i < params::opt / 2; ++i) {
+#pragma unroll
+  for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+    tid = threadIdx.x + i * params::degree / params::opt;
+    twid_id = tid / (params::degree / 64);
+    i1 =
+        2 * (params::degree / 64) * twid_id + (tid & (params::degree / 64 - 1));
+    i2 = i1 + params::degree / 64;
+
+    w = negtwiddles[twid_id + 32];
+    u = A[i1];
+    v = A[i2] * w;
+
+    A[i1] += v;
+    A[i2] = u - v;
+    //tid += params::degree / params::opt;
+  }
+  __syncthreads();
+
+  // level 7
+  tid = threadIdx.x;
+#pragma unroll
+  for (size_t i = 0; i < params::opt / 2; ++i) {
+    twid_id = tid / (params::degree / 128);
+    i1 = 2 * (params::degree / 128) * twid_id +
+         (tid & (params::degree / 128 - 1));
+    i2 = i1 + params::degree / 128;
+
+    w = negtwiddles[twid_id + 64];
+    u = A[i1];
+    v = A[i2] * w;
+
+    A[i1] += v;
+    A[i2] = u - v;
+
+    tid += params::degree / params::opt;
+  }
+  __syncthreads();
+
+  // from level 8, we need to check size of params degree, because we support
+  // minimum actual polynomial size = 256,  when compressed size is halfed and
+  // minimum supported compressed size is 128, so we always need first 7
+  // levels of butterfly operation, since butterfly levels are hardcoded
+  // we need to check if polynomial size is big enough to require specific level
+  // of butterfly.
+  if constexpr (params::degree >= 256) {
+    // level 8
+    //tid = threadIdx.x;
+    //for (size_t i = 0; i < params::opt / 2; ++i) {
+#pragma unroll
+    for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+      tid = threadIdx.x + i * params::degree / params::opt;
+      twid_id = tid / (params::degree / 256);
+      i1 = 2 * (params::degree / 256) * twid_id +
+           (tid & (params::degree / 256 - 1));
+      i2 = i1 + params::degree / 256;
+
+      w = negtwiddles[twid_id + 128];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      //tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+
+  if constexpr (params::degree >= 512) {
+    // level 9
+    tid = threadIdx.x;
+#pragma unroll
+    for (size_t i = 0; i < params::opt / 2; ++i) {
+      twid_id = tid / (params::degree / 512);
+      i1 = 2 * (params::degree / 512) * twid_id +
+           (tid & (params::degree / 512 - 1));
+      i2 = i1 + params::degree / 512;
+
+      w = negtwiddles[twid_id + 256];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+
+  if constexpr (params::degree >= 1024) {
+    // level 10
+    //tid = threadIdx.x;
+    //for (size_t i = 0; i < params::opt / 2; ++i) {
+#pragma unroll
+    for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+      tid = threadIdx.x + i * params::degree / params::opt;
+      twid_id = tid / (params::degree / 1024);
+      i1 = 2 * (params::degree / 1024) * twid_id +
+           (tid & (params::degree / 1024 - 1));
+      i2 = i1 + params::degree / 1024;
+
+      w = negtwiddles[twid_id + 512];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      //tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+
+  if constexpr (params::degree >= 2048) {
+    // level 11
+    tid = threadIdx.x;
+#pragma unroll
+    for (size_t i = 0; i < params::opt / 2; ++i) {
+      twid_id = tid / (params::degree / 2048);
+      i1 = 2 * (params::degree / 2048) * twid_id +
+           (tid & (params::degree / 2048 - 1));
+      i2 = i1 + params::degree / 2048;
+
+      w = negtwiddles[twid_id + 1024];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+
+  if constexpr (params::degree >= 4096) {
+    // level 12
+    //tid = threadIdx.x;
+    //for (size_t i = 0; i < params::opt / 2; ++i) {
+#pragma unroll
+    for (int i = params::opt / 2 - 1; i >= 0 ; --i) {
+      tid = threadIdx.x + i * params::degree / params::opt;
+      twid_id = tid / (params::degree / 4096);
+      i1 = 2 * (params::degree / 4096) * twid_id +
+           (tid & (params::degree / 4096 - 1));
+      i2 = i1 + params::degree / 4096;
+
+      w = negtwiddles[twid_id + 2048];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      //tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+
+  if constexpr (params::degree >= 8192) {
+    // level 13
+    tid = threadIdx.x;
+#pragma unroll
+    for (size_t i = 0; i < params::opt / 2; ++i) {
+      twid_id = tid / (params::degree / 8192);
+      i1 = 2 * (params::degree / 8192) * twid_id +
+           (tid & (params::degree / 8192 - 1));
+      i2 = i1 + params::degree / 8192;
+
+      w = negtwiddles[twid_id + 4096];
+      u = A[i1];
+      v = A[i2] * w;
+
+      A[i1] += v;
+      A[i2] = u - v;
+
+      tid += params::degree / params::opt;
+    }
+    __syncthreads();
+  }
+}
+
 #endif // GPU_BOOTSTRAP_FFT_CUH
diff --git a/backends/tfhe-cuda-backend/cuda/src/pbs/programmable_bootstrap_multibit.cuh b/backends/tfhe-cuda-backend/cuda/src/pbs/programmable_bootstrap_multibit.cuh
index 8b8abc0f71..006c257876 100644
--- a/backends/tfhe-cuda-backend/cuda/src/pbs/programmable_bootstrap_multibit.cuh
+++ b/backends/tfhe-cuda-backend/cuda/src/pbs/programmable_bootstrap_multibit.cuh
@@ -84,6 +84,7 @@ __global__ void device_multi_bit_programmable_bootstrap_keybundle(
         grouping_factor, 2 * polynomial_size, glwe_dimension, level_count);
     Torus *bsk_poly = bsk_slice + poly_id * params::degree;
 
+    // opt = 8 degree/opt = 256
     copy_polynomial<Torus, params::opt, params::degree / params::opt>(
         bsk_poly, accumulator);
 
@@ -114,6 +115,7 @@ __global__ void device_multi_bit_programmable_bootstrap_keybundle(
     // Move accumulator to local memory
     double2 temp[params::opt / 2];
     int tid = threadIdx.x;
+    //opt = 8 degree=2048  degree/opt =256
 #pragma unroll
     for (int i = 0; i < params::opt / 2; i++) {
       temp[i].x = __ll2double_rn((int64_t)accumulator[tid]);
@@ -123,17 +125,22 @@ __global__ void device_multi_bit_programmable_bootstrap_keybundle(
       temp[i].y /= (double)std::numeric_limits<Torus>::max();
       tid += params::degree / params::opt;
     }
-
+/*
     synchronize_threads_in_block();
+    
     // Move from local memory back to shared memory but as complex
     tid = threadIdx.x;
+    //Loop for 4 times ... temp[4]
+
 #pragma unroll
     for (int i = 0; i < params::opt / 2; i++) {
       fft[tid] = temp[i];
-      tid += params::degree / params::opt;
+      tid += params::degree / params::opt; // degree 2048 opt 8  degree/opt = 256
     }
     synchronize_threads_in_block();
     NSMFFT_direct<HalfDegree<params>>(fft);
+*/
+    NSMFFT_direct_bundle<HalfDegree<params>>(fft, temp);
 
     // lwe iteration
     auto keybundle_out = get_ith_mask_kth_block(