diff --git a/av1/av1.cmake b/av1/av1.cmake
index 4b92eb4..5e730f9 100644
--- a/av1/av1.cmake
+++ b/av1/av1.cmake
@@ -363,7 +363,6 @@
             "${AOM_ROOT}/av1/encoder/x86/av1_fwd_txfm2d_sse4.c"
             "${AOM_ROOT}/av1/encoder/x86/encodetxb_sse4.c"
             "${AOM_ROOT}/av1/encoder/x86/highbd_fwd_txfm_sse4.c"
-            "${AOM_ROOT}/av1/encoder/x86/model_rd_sse4.c"
             "${AOM_ROOT}/av1/encoder/x86/rdopt_sse4.c"
             "${AOM_ROOT}/av1/encoder/x86/pickrst_sse4.c")
 
diff --git a/av1/common/av1_rtcd_defs.pl b/av1/common/av1_rtcd_defs.pl
index 2e7acf3..78e6429 100644
--- a/av1/common/av1_rtcd_defs.pl
+++ b/av1/common/av1_rtcd_defs.pl
@@ -460,9 +460,6 @@
   add_proto qw/void av1_get_horver_correlation_full/, "const int16_t *diff, int stride, int w, int h, float *hcorr, float *vcorr";
   specialize qw/av1_get_horver_correlation_full sse4_1 avx2 neon/;
 
-  add_proto qw/void av1_interp_cubic_rate_dist/, "const double *p1, const double *p2, double x, double * const rate_f, double * const distbysse_f";
-  specialize qw/av1_interp_cubic_rate_dist sse4_1/;
-
   add_proto qw/void av1_nn_predict/, "const float *input_nodes, const NN_CONFIG *const nn_config, int reduce_prec, float *const output";
 
   add_proto qw/void av1_nn_fast_softmax_16/, "const float *input_nodes, float *output";
diff --git a/av1/encoder/rd.c b/av1/encoder/rd.c
index b5f6b3a..e9f6e54 100644
--- a/av1/encoder/rd.c
+++ b/av1/encoder/rd.c
@@ -949,13 +949,6 @@
                           x * (3.0 * (p[1] - p[2]) + p[3] - p[0])));
 }
 
-void av1_interp_cubic_rate_dist_c(const double *p1, const double *p2, double x,
-                                  double *const rate_f,
-                                  double *const distbysse_f) {
-  *rate_f = interp_cubic(p1, x);
-  *distbysse_f = interp_cubic(p2, x);
-}
-
 /*
 static double interp_bicubic(const double *p, int p_stride, double x,
                              double y) {
@@ -1087,8 +1080,9 @@
   assert(xi > 0);
 
   const double *prate = &interp_rgrid_curv[rcat][(xi - 1)];
+  *rate_f = interp_cubic(prate, xo);
   const double *pdist = &interp_dgrid_curv[dcat][(xi - 1)];
-  av1_interp_cubic_rate_dist(prate, pdist, xo, rate_f, distbysse_f);
+  *distbysse_f = interp_cubic(pdist, xo);
 }
 
 static void get_entropy_contexts_plane(BLOCK_SIZE plane_bsize,
diff --git a/av1/encoder/x86/model_rd_sse4.c b/av1/encoder/x86/model_rd_sse4.c
deleted file mode 100644
index 48bc580..0000000
--- a/av1/encoder/x86/model_rd_sse4.c
+++ /dev/null
@@ -1,64 +0,0 @@
-/*
- * Copyright (c) 2026, Alliance for Open Media. All rights reserved.
- *
- * This source code is subject to the terms of the BSD 2 Clause License and
- * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
- * was not distributed with this source code in the LICENSE file, you can
- * obtain it at www.aomedia.org/license/software. If the Alliance for Open
- * Media Patent License 1.0 was not distributed with this source code in the
- * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
- */
-
-#include <smmintrin.h>
-
-#include "config/av1_rtcd.h"
-
-void av1_interp_cubic_rate_dist_sse4_1(const double *p1, const double *p2,
-                                       double x, double *const rate_f,
-                                       double *const distbysse_f) {
-  const __m128d half = _mm_set1_pd(0.5);
-  const __m128d two = _mm_set1_pd(2.0);
-  const __m128d three = _mm_set1_pd(3.0);
-  const __m128d four = _mm_set1_pd(4.0);
-  const __m128d five = _mm_set1_pd(5.0);
-
-  const __m128d reg_x = _mm_set1_pd(x);
-  const __m128d reg_p0 = _mm_set_pd(p2[0], p1[0]);
-  const __m128d reg_p1 = _mm_set_pd(p2[1], p1[1]);
-  const __m128d reg_p2 = _mm_set_pd(p2[2], p1[2]);
-  const __m128d reg_p3 = _mm_set_pd(p2[3], p1[3]);
-
-  // To ensure that results are bit-identical to the C code, we need to perform
-  // exactly the same sequence of operations here as in the C code.
-  // reg_res_0 = x * (3.0 * (p[1] - p[2]) + p[3] - p[0])
-  __m128d reg_res_0 = _mm_sub_pd(reg_p1, reg_p2);
-  reg_res_0 = _mm_mul_pd(three, reg_res_0);
-  reg_res_0 = _mm_add_pd(reg_res_0, reg_p3);
-  reg_res_0 = _mm_sub_pd(reg_res_0, reg_p0);
-  reg_res_0 = _mm_mul_pd(reg_x, reg_res_0);
-
-  // reg_res_1 = 2.0 * p[0] - 5.0 * p[1] + 4.0 * p[2]- p[3]
-  const __m128d regp0_x_2 = _mm_mul_pd(two, reg_p0);
-  const __m128d regp1_x_5 = _mm_mul_pd(five, reg_p1);
-  const __m128d regp2_x_4 = _mm_mul_pd(four, reg_p2);
-  __m128d reg_res_1 = _mm_sub_pd(regp0_x_2, regp1_x_5);
-  reg_res_1 = _mm_add_pd(reg_res_1, regp2_x_4);
-  reg_res_1 = _mm_sub_pd(reg_res_1, reg_p3);
-
-  // reg_res_2 = x * (reg_res_1 + reg_res_0)
-  __m128d reg_res_2 = _mm_add_pd(reg_res_1, reg_res_0);
-  reg_res_2 = _mm_mul_pd(reg_x, reg_res_2);
-
-  // reg_res_3 = p[2] - p[0] + reg_res_2
-  __m128d reg_res_3 = _mm_sub_pd(reg_p2, reg_p0);
-  reg_res_3 = _mm_add_pd(reg_res_3, reg_res_2);
-
-  // reg_res_4 = p[1] + 0.5 * x * reg_res_3
-  __m128d reg_res_4 = _mm_mul_pd(_mm_mul_pd(half, reg_x), reg_res_3);
-  reg_res_4 = _mm_add_pd(reg_p1, reg_res_4);
-
-  double result[2];
-  _mm_storeu_pd(result, reg_res_4);
-  *rate_f = result[0];
-  *distbysse_f = result[1];
-}
diff --git a/test/model_rd_test.cc b/test/model_rd_test.cc
deleted file mode 100644
index 910f20a..0000000
--- a/test/model_rd_test.cc
+++ /dev/null
@@ -1,114 +0,0 @@
-/*
- * Copyright (c) 2026, Alliance for Open Media. All rights reserved.
- *
- * This source code is subject to the terms of the BSD 2 Clause License and
- * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
- * was not distributed with this source code in the LICENSE file, you can
- * obtain it at www.aomedia.org/license/software. If the Alliance for Open
- * Media Patent License 1.0 was not distributed with this source code in the
- * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
- */
-
-#include <cstdlib>
-
-#include "gtest/gtest.h"
-#include "config/av1_rtcd.h"
-
-#include "test/acm_random.h"
-#include "test/register_state_check.h"
-#include "test/util.h"
-
-using libaom_test::ACMRandom;
-
-namespace {
-
-using InterpCubicRateDistFunc = void (*)(const double *p1, const double *p2,
-                                         double x, double *const rate_f,
-                                         double *const distbysse_f);
-
-using InterpCubicTestParam = std::tuple<const InterpCubicRateDistFunc>;
-
-class InterpCubicTest : public ::testing::TestWithParam<InterpCubicTestParam> {
- public:
-  double generate_random_double(double min, double max) {
-    return min + (static_cast<double>(rnd_.Rand31()) / ((1U << 31) - 1)) *
-                     (max - min);
-  }
-  void SetUp() override { target_func_ = GET_PARAM(0); }
-  void TearDown() override {}
-  void CheckOutput();
-  void SpeedTest();
-
- protected:
-  InterpCubicRateDistFunc target_func_;
-
- private:
-  libaom_test::ACMRandom rnd_;
-};
-GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(InterpCubicTest);
-
-void InterpCubicTest::CheckOutput() {
-  double p1[4], p2[4];
-  double rate_f_ref, rate_f_mod, distbysse_f_ref, distbysse_f_mod;
-  const int knum_iter = 10000;
-  for (int iter = 0; iter < knum_iter; iter++) {
-    for (int i = 0; i < 4; i++) {
-      p1[i] = generate_random_double(0.0000, 4096.000000);
-      p2[i] = generate_random_double(0.0000, 16.0000);
-    }
-    double x = generate_random_double(0.0000, 1.0000);
-
-    av1_interp_cubic_rate_dist_c(p1, p2, x, &rate_f_ref, &distbysse_f_ref);
-    target_func_(p1, p2, x, &rate_f_mod, &distbysse_f_mod);
-    EXPECT_EQ(rate_f_ref, rate_f_mod) << "Error: rate_f value mismatch";
-    EXPECT_EQ(distbysse_f_ref, distbysse_f_mod)
-        << "Error: distbysse_f value mismatch";
-  }
-}
-
-void InterpCubicTest::SpeedTest() {
-  double p1[4], p2[4];
-  double rate_f_ref, rate_f_mod, distbysse_f_ref, distbysse_f_mod;
-
-  for (int i = 0; i < 4; i++) {
-    p1[i] = generate_random_double(0.0000, 4096.0000);
-    p2[i] = generate_random_double(0.0000, 16.0000);
-  }
-  double x = generate_random_double(0.0000, 1.0000);
-
-  const int num_iter = 100000000;
-
-  aom_usec_timer ref_timer, test_timer;
-  aom_usec_timer_start(&ref_timer);
-  for (int iter = 0; iter < num_iter; iter++) {
-    av1_interp_cubic_rate_dist_c(p1, p2, x, &rate_f_ref, &distbysse_f_ref);
-  }
-  aom_usec_timer_mark(&ref_timer);
-  const int elapsed_time_c =
-      static_cast<int>(aom_usec_timer_elapsed(&ref_timer));
-
-  aom_usec_timer_start(&test_timer);
-  for (int iter = 0; iter < num_iter; iter++) {
-    target_func_(p1, p2, x, &rate_f_mod, &distbysse_f_mod);
-  }
-  aom_usec_timer_mark(&test_timer);
-  const int elapsed_time_simd =
-      static_cast<int>(aom_usec_timer_elapsed(&test_timer));
-
-  printf(
-      " c_time=%d \t simd_time=%d \t "
-      "Scaling=%lf \n",
-      elapsed_time_c, elapsed_time_simd,
-      (static_cast<double>(elapsed_time_c) / elapsed_time_simd));
-}
-
-TEST_P(InterpCubicTest, CheckOutput) { CheckOutput(); }
-
-TEST_P(InterpCubicTest, DISABLED_Speed) { SpeedTest(); }
-
-#if HAVE_SSE4_1
-INSTANTIATE_TEST_SUITE_P(SSE4_1, InterpCubicTest,
-                         ::testing::Values(av1_interp_cubic_rate_dist_sse4_1));
-#endif  // HAVE_SSE4_1
-
-}  // namespace
diff --git a/test/test.cmake b/test/test.cmake
index 84ba918..6224c54 100644
--- a/test/test.cmake
+++ b/test/test.cmake
@@ -232,7 +232,6 @@
               "${AOM_ROOT}/test/masked_variance_test.cc"
               "${AOM_ROOT}/test/metadata_test.cc"
               "${AOM_ROOT}/test/minmax_test.cc"
-              "${AOM_ROOT}/test/model_rd_test.cc"
               "${AOM_ROOT}/test/motion_vector_test.cc"
               "${AOM_ROOT}/test/mv_cost_test.cc"
               "${AOM_ROOT}/test/obmc_sad_test.cc"