diff --git a/src/layer/arm/convolution_3x3_pack1to4.h b/src/layer/arm/convolution_3x3_pack1to4.h
index f515cc1d3..977766d87 100644
--- a/src/layer/arm/convolution_3x3_pack1to4.h
+++ b/src/layer/arm/convolution_3x3_pack1to4.h
@@ -21,8 +21,359 @@ static void conv3x3s1_pack1to4_neon(const Mat& bottom_blob, Mat& top_blob, const
 
     const float* bias = _bias;
 
+    int nn_outch = 0;
+    int remain_outch_start = 0;
+
+#if __ARM_NEON && __aarch64__
+    nn_outch = outch >> 1;
+    remain_outch_start = nn_outch << 1;
+
     #pragma omp parallel for num_threads(opt.num_threads)
-    for (int p=0; p<outch; p++)
+    for (int pp=0; pp<nn_outch; pp++)
+    {
+        int p = pp * 2;
+
+        Mat out0 = top_blob.channel(p);
+        Mat out1 = top_blob.channel(p+1);
+
+        float32x4_t _bias0 = bias ? vld1q_f32((const float*)bias + p * 4) : vdupq_n_f32(0.f);
+        float32x4_t _bias1 = bias ? vld1q_f32((const float*)bias + (p+1) * 4) : vdupq_n_f32(0.f);
+        out0.fill(_bias0);
+        out1.fill(_bias1);
+
+        const float* k0 = kernel.channel(p);
+        const float* k1 = kernel.channel(p+1);
+
+        for (int q=0; q<inch; q++)
+        {
+            float* outptr0 = out0;
+            float* outptr1 = out1;
+
+            const Mat img0 = bottom_blob.channel(q);
+
+            const float* r0 = img0.row(0);
+            const float* r1 = img0.row(1);
+            const float* r2 = img0.row(2);
+
+            float32x4_t _k00_0 = vld1q_f32(k0);
+            float32x4_t _k01_0 = vld1q_f32(k0+4);
+            float32x4_t _k02_0 = vld1q_f32(k0+8);
+            float32x4_t _k10_0 = vld1q_f32(k0+12);
+            float32x4_t _k11_0 = vld1q_f32(k0+16);
+            float32x4_t _k12_0 = vld1q_f32(k0+20);
+            float32x4_t _k20_0 = vld1q_f32(k0+24);
+            float32x4_t _k21_0 = vld1q_f32(k0+28);
+            float32x4_t _k22_0 = vld1q_f32(k0+32);
+
+            float32x4_t _k00_1 = vld1q_f32(k1);
+            float32x4_t _k01_1 = vld1q_f32(k1+4);
+            float32x4_t _k02_1 = vld1q_f32(k1+8);
+            float32x4_t _k10_1 = vld1q_f32(k1+12);
+            float32x4_t _k11_1 = vld1q_f32(k1+16);
+            float32x4_t _k12_1 = vld1q_f32(k1+20);
+            float32x4_t _k20_1 = vld1q_f32(k1+24);
+            float32x4_t _k21_1 = vld1q_f32(k1+28);
+            float32x4_t _k22_1 = vld1q_f32(k1+32);
+
+            int i = 0;
+
+            for (; i < outh; i++)
+            {
+                int j = 0;
+
+                for (; j+3<outw; j+=4)
+                {
+                    asm volatile(
+                        "prfm   pldl1keep, [%0, #512]       \n"
+                        "ld1    {v24.4s, v25.4s, v26.4s, v27.4s}, [%0] \n"
+
+                        "prfm   pldl1keep, [%1, #512]       \n"
+                        "ld1    {v28.4s, v29.4s, v30.4s, v31.4s}, [%1] \n"
+
+                        "prfm   pldl1keep, [%2, #128]       \n"
+                        "ld1    {v0.4s}, [%2], #16          \n"
+
+                        "ld1    {v1.2s}, [%2]               \n"
+
+                        "fmla   v24.4s, %10.4s, v0.s[0]     \n"
+                        "fmla   v25.4s, %10.4s, v0.s[1]     \n"
+                        "fmla   v26.4s, %10.4s, v0.s[2]     \n"
+                        "fmla   v27.4s, %10.4s, v0.s[3]     \n"
+                        "fmla   v28.4s, %19.4s, v0.s[0]     \n"
+                        "fmla   v29.4s, %19.4s, v0.s[1]     \n"
+                        "fmla   v30.4s, %19.4s, v0.s[2]     \n"
+                        "fmla   v31.4s, %19.4s, v0.s[3]     \n"
+
+                        "fmla   v24.4s, %11.4s, v0.s[1]     \n"
+                        "fmla   v25.4s, %11.4s, v0.s[2]     \n"
+                        "fmla   v26.4s, %11.4s, v0.s[3]     \n"
+                        "fmla   v27.4s, %11.4s, v1.s[0]     \n"
+                        "fmla   v28.4s, %20.4s, v0.s[1]     \n"
+                        "fmla   v29.4s, %20.4s, v0.s[2]     \n"
+                        "fmla   v30.4s, %20.4s, v0.s[3]     \n"
+                        "fmla   v31.4s, %20.4s, v1.s[0]     \n"
+
+                        "prfm   pldl1keep, [%3, #128]       \n"
+                        "ld1    {v2.4s}, [%3], #16          \n"
+
+                        "ld1    {v3.2s}, [%3]               \n"
+
+                        "fmla   v24.4s, %12.4s, v0.s[2]     \n"
+                        "fmla   v25.4s, %12.4s, v0.s[3]     \n"
+                        "fmla   v26.4s, %12.4s, v1.s[0]     \n"
+                        "fmla   v27.4s, %12.4s, v1.s[1]     \n"
+                        "fmla   v28.4s, %21.4s, v0.s[2]     \n"
+                        "fmla   v29.4s, %21.4s, v0.s[3]     \n"
+                        "fmla   v30.4s, %21.4s, v1.s[0]     \n"
+                        "fmla   v31.4s, %21.4s, v1.s[1]     \n"
+
+                        "fmla   v24.4s, %13.4s, v2.s[0]     \n"
+                        "fmla   v25.4s, %13.4s, v2.s[1]     \n"
+                        "fmla   v26.4s, %13.4s, v2.s[2]     \n"
+                        "fmla   v27.4s, %13.4s, v2.s[3]     \n"
+                        "fmla   v28.4s, %22.4s, v2.s[0]     \n"
+                        "fmla   v29.4s, %22.4s, v2.s[1]     \n"
+                        "fmla   v30.4s, %22.4s, v2.s[2]     \n"
+                        "fmla   v31.4s, %22.4s, v2.s[3]     \n"
+
+                        "fmla   v24.4s, %14.4s, v2.s[1]     \n"
+                        "fmla   v25.4s, %14.4s, v2.s[2]     \n"
+                        "fmla   v26.4s, %14.4s, v2.s[3]     \n"
+                        "fmla   v27.4s, %14.4s, v3.s[0]     \n"
+                        "fmla   v28.4s, %23.4s, v2.s[1]     \n"
+                        "fmla   v29.4s, %23.4s, v2.s[2]     \n"
+                        "fmla   v30.4s, %23.4s, v2.s[3]     \n"
+                        "fmla   v31.4s, %23.4s, v3.s[0]     \n"
+
+                        "prfm   pldl1keep, [%4, #128]       \n"
+                        "ld1    {v0.4s}, [%4], #16          \n"
+
+                        "ld1    {v1.2s}, [%4]               \n"
+
+                        "fmla   v24.4s, %15.4s, v2.s[2]     \n"
+                        "fmla   v25.4s, %15.4s, v2.s[3]     \n"
+                        "fmla   v26.4s, %15.4s, v3.s[0]     \n"
+                        "fmla   v27.4s, %15.4s, v3.s[1]     \n"
+                        "fmla   v28.4s, %24.4s, v2.s[2]     \n"
+                        "fmla   v29.4s, %24.4s, v2.s[3]     \n"
+                        "fmla   v30.4s, %24.4s, v3.s[0]     \n"
+                        "fmla   v31.4s, %24.4s, v3.s[1]     \n"
+
+                        "fmla   v24.4s, %16.4s, v0.s[0]     \n"
+                        "fmla   v25.4s, %16.4s, v0.s[1]     \n"
+                        "fmla   v26.4s, %16.4s, v0.s[2]     \n"
+                        "fmla   v27.4s, %16.4s, v0.s[3]     \n"
+                        "fmla   v28.4s, %25.4s, v0.s[0]     \n"
+                        "fmla   v29.4s, %25.4s, v0.s[1]     \n"
+                        "fmla   v30.4s, %25.4s, v0.s[2]     \n"
+                        "fmla   v31.4s, %25.4s, v0.s[3]     \n"
+
+                        "fmla   v24.4s, %17.4s, v0.s[1]     \n"
+                        "fmla   v25.4s, %17.4s, v0.s[2]     \n"
+                        "fmla   v26.4s, %17.4s, v0.s[3]     \n"
+                        "fmla   v27.4s, %17.4s, v1.s[0]     \n"
+                        "fmla   v28.4s, %26.4s, v0.s[1]     \n"
+                        "fmla   v29.4s, %26.4s, v0.s[2]     \n"
+                        "fmla   v30.4s, %26.4s, v0.s[3]     \n"
+                        "fmla   v31.4s, %26.4s, v1.s[0]     \n"
+
+                        "fmla   v24.4s, %18.4s, v0.s[2]     \n"
+                        "fmla   v25.4s, %18.4s, v0.s[3]     \n"
+                        "fmla   v26.4s, %18.4s, v1.s[0]     \n"
+                        "fmla   v27.4s, %18.4s, v1.s[1]     \n"
+                        "fmla   v28.4s, %27.4s, v0.s[2]     \n"
+                        "fmla   v29.4s, %27.4s, v0.s[3]     \n"
+                        "fmla   v30.4s, %27.4s, v1.s[0]     \n"
+                        "fmla   v31.4s, %27.4s, v1.s[1]     \n"
+
+                        "st1    {v24.4s, v25.4s, v26.4s, v27.4s}, [%0], #64 \n"
+                        "st1    {v28.4s, v29.4s, v30.4s, v31.4s}, [%1], #64 \n"
+
+                        : "=r"(outptr0),    // %0
+                          "=r"(outptr1),    // %1
+                          "=r"(r0),         // %2
+                          "=r"(r1),         // %3
+                          "=r"(r2)          // %4
+                        : "0"(outptr0),
+                          "1"(outptr1),
+                          "2"(r0),
+                          "3"(r1),
+                          "4"(r2),
+                          "w"(_k00_0),      // %10
+                          "w"(_k01_0),      // %11
+                          "w"(_k02_0),      // %12
+                          "w"(_k10_0),      // %13
+                          "w"(_k11_0),      // %14
+                          "w"(_k12_0),      // %15
+                          "w"(_k20_0),      // %16
+                          "w"(_k21_0),      // %17
+                          "w"(_k22_0),      // %18
+                          "w"(_k00_1),      // %19
+                          "w"(_k01_1),      // %20
+                          "w"(_k02_1),      // %21
+                          "w"(_k10_1),      // %22
+                          "w"(_k11_1),      // %23
+                          "w"(_k12_1),      // %24
+                          "w"(_k20_1),      // %25
+                          "w"(_k21_1),      // %26
+                          "w"(_k22_1)       // %27
+                        : "memory", "v0", "v1", "v2", "v3", "v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31"
+                    );
+                }
+                for (; j+1<outw; j+=2)
+                {
+                    asm volatile(
+                        "prfm   pldl1keep, [%0, #256]       \n"
+                        "ld1    {v24.4s, v25.4s}, [%0]      \n"
+
+                        "prfm   pldl1keep, [%1, #256]       \n"
+                        "ld1    {v26.4s, v27.4s}, [%1]      \n"
+
+                        "prfm   pldl1keep, [%2, #128]       \n"
+                        "ld1    {v0.4s}, [%2]               \n"
+                        "add    %2, %2, #8                  \n"
+
+                        "fmla   v24.4s, %10.4s, v0.s[0]     \n"
+                        "fmla   v25.4s, %10.4s, v0.s[1]     \n"
+                        "fmla   v26.4s, %19.4s, v0.s[0]     \n"
+                        "fmla   v27.4s, %19.4s, v0.s[1]     \n"
+
+                        "fmla   v24.4s, %11.4s, v0.s[1]     \n"
+                        "fmla   v25.4s, %11.4s, v0.s[2]     \n"
+                        "fmla   v26.4s, %20.4s, v0.s[1]     \n"
+                        "fmla   v27.4s, %20.4s, v0.s[2]     \n"
+
+                        "prfm   pldl1keep, [%3, #128]       \n"
+                        "ld1    {v1.4s}, [%3]               \n"
+
+                        "fmla   v24.4s, %12.4s, v0.s[2]     \n"
+                        "fmla   v25.4s, %12.4s, v0.s[3]     \n"
+                        "fmla   v26.4s, %21.4s, v0.s[2]     \n"
+                        "fmla   v27.4s, %21.4s, v0.s[3]     \n"
+
+                        "add    %3, %3, #8                  \n"
+
+                        "fmla   v24.4s, %13.4s, v1.s[0]     \n"
+                        "fmla   v25.4s, %13.4s, v1.s[1]     \n"
+                        "fmla   v26.4s, %22.4s, v1.s[0]     \n"
+                        "fmla   v27.4s, %22.4s, v1.s[1]     \n"
+
+                        "fmla   v24.4s, %14.4s, v1.s[1]     \n"
+                        "fmla   v25.4s, %14.4s, v1.s[2]     \n"
+                        "fmla   v26.4s, %23.4s, v1.s[1]     \n"
+                        "fmla   v27.4s, %23.4s, v1.s[2]     \n"
+
+                        "prfm   pldl1keep, [%4, #128]       \n"
+                        "ld1    {v0.4s}, [%4]               \n"
+
+                        "fmla   v24.4s, %15.4s, v1.s[2]     \n"
+                        "fmla   v25.4s, %15.4s, v1.s[3]     \n"
+                        "fmla   v26.4s, %24.4s, v1.s[2]     \n"
+                        "fmla   v27.4s, %24.4s, v1.s[3]     \n"
+
+                        "add    %4, %4, #8                  \n"
+
+                        "fmla   v24.4s, %16.4s, v0.s[0]     \n"
+                        "fmla   v25.4s, %16.4s, v0.s[1]     \n"
+                        "fmla   v26.4s, %25.4s, v0.s[0]     \n"
+                        "fmla   v27.4s, %25.4s, v0.s[1]     \n"
+
+                        "fmla   v24.4s, %17.4s, v0.s[1]     \n"
+                        "fmla   v25.4s, %17.4s, v0.s[2]     \n"
+                        "fmla   v26.4s, %26.4s, v0.s[1]     \n"
+                        "fmla   v27.4s, %26.4s, v0.s[2]     \n"
+
+                        "fmla   v24.4s, %18.4s, v0.s[2]     \n"
+                        "fmla   v25.4s, %18.4s, v0.s[3]     \n"
+                        "fmla   v26.4s, %27.4s, v0.s[2]     \n"
+                        "fmla   v27.4s, %27.4s, v0.s[3]     \n"
+
+                        "st1    {v24.4s, v25.4s}, [%0], #32 \n"
+                        "st1    {v26.4s, v27.4s}, [%1], #32 \n"
+
+                        : "=r"(outptr0),    // %0
+                          "=r"(outptr1),    // %1
+                          "=r"(r0),         // %2
+                          "=r"(r1),         // %3
+                          "=r"(r2)          // %4
+                        : "0"(outptr0),
+                          "1"(outptr1),
+                          "2"(r0),
+                          "3"(r1),
+                          "4"(r2),
+                          "w"(_k00_0),      // %10
+                          "w"(_k01_0),      // %11
+                          "w"(_k02_0),      // %12
+                          "w"(_k10_0),      // %13
+                          "w"(_k11_0),      // %14
+                          "w"(_k12_0),      // %15
+                          "w"(_k20_0),      // %16
+                          "w"(_k21_0),      // %17
+                          "w"(_k22_0),      // %18
+                          "w"(_k00_1),      // %19
+                          "w"(_k01_1),      // %20
+                          "w"(_k02_1),      // %21
+                          "w"(_k10_1),      // %22
+                          "w"(_k11_1),      // %23
+                          "w"(_k12_1),      // %24
+                          "w"(_k20_1),      // %25
+                          "w"(_k21_1),      // %26
+                          "w"(_k22_1)       // %27
+                        : "memory", "v0", "v1", "v24", "v25", "v26", "v27"
+                    );
+                }
+                for (; j<outw; j++)
+                {
+                    float32x4_t _sum00 = vld1q_f32(outptr0);
+                    float32x4_t _sum10 = vld1q_f32(outptr1);
+
+                    float32x4_t _r0 = vld1q_f32(r0);
+                    float32x4_t _r1 = vld1q_f32(r1);
+                    float32x4_t _r2 = vld1q_f32(r2);
+
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k00_0, _r0, 0);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k01_0, _r0, 1);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k02_0, _r0, 2);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k10_0, _r1, 0);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k11_0, _r1, 1);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k12_0, _r1, 2);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k20_0, _r2, 0);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k21_0, _r2, 1);
+                    _sum00 = vfmaq_laneq_f32(_sum00, _k22_0, _r2, 2);
+
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k00_1, _r0, 0);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k01_1, _r0, 1);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k02_1, _r0, 2);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k10_1, _r1, 0);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k11_1, _r1, 1);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k12_1, _r1, 2);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k20_1, _r2, 0);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k21_1, _r2, 1);
+                    _sum10 = vfmaq_laneq_f32(_sum10, _k22_1, _r2, 2);
+
+                    vst1q_f32(outptr0, _sum00);
+                    vst1q_f32(outptr1, _sum10);
+
+                    r0 += 1;
+                    r1 += 1;
+                    r2 += 1;
+                    outptr0 += 4;
+                    outptr1 += 4;
+                }
+
+                r0 += 2;
+                r1 += 2;
+                r2 += 2;
+            }
+
+            k0 += 9*4;
+            k1 += 9*4;
+        }
+    }
+#endif // __ARM_NEON && __aarch64__
+
+    #pragma omp parallel for num_threads(opt.num_threads)
+    for (int p=remain_outch_start; p<outch; p++)
     {
         Mat out0 = top_blob.channel(p);