diff --git a/src/video_core/host_shaders/astc_decoder.comp b/src/video_core/host_shaders/astc_decoder.comp
index da21b4bde8..f0358f5330 100644
--- a/src/video_core/host_shaders/astc_decoder.comp
+++ b/src/video_core/host_shaders/astc_decoder.comp
@@ -83,6 +83,12 @@ int result_index = 0;
 uint result_vector_max_index;
 bool result_limit_reached = false;
 
+// avoid intermediate result_vector storage during color decode phase
+bool write_color_values = false;
+uint color_values_direct[32];
+uint color_out_index = 0;
+uint color_num_values = 0;
+
 // EncodingData helpers
 uint Encoding(EncodingData val) {
     return bitfieldExtract(val.data, 0, 8);
@@ -114,9 +120,110 @@ EncodingData CreateEncodingData(uint encoding, uint num_bits, uint bit_val, uint
     return EncodingData(((encoding) << 0u) | ((num_bits) << 8u) |
                         ((bit_val) << 16u) | ((quint_trit_val) << 24u));
 }
+uint ReplicateBitTo9(uint bit);
+uint FastReplicateTo8(uint value, uint num_bits);
+
+void EmitColorValue(EncodingData val) {
+    // write directly to color_values_direct[]
+    const uint encoding = Encoding(val);
+    const uint bitlen = NumBits(val);
+    const uint bitval = BitValue(val);
+
+    if (encoding == JUST_BITS) {
+        color_values_direct[++color_out_index] = FastReplicateTo8(bitval, bitlen);
+        return;
+    }
+
+    uint A = ReplicateBitTo9((bitval & 1));
+    uint B = 0, C = 0, D = QuintTritValue(val);
+
+    if (encoding == TRIT) {
+        switch (bitlen) {
+            case 1:
+            C = 204;
+            break;
+            case 2: {
+                C = 93;
+                const uint b = (bitval >> 1) & 1;
+                B = (b << 8) | (b << 4) | (b << 2) | (b << 1);
+                break;
+            }
+            case 3: {
+                C = 44;
+                const uint cb = (bitval >> 1) & 3;
+                B = (cb << 7) | (cb << 2) | cb;
+                break;
+            }
+            case 4: {
+                C = 22;
+                const uint dcb = (bitval >> 1) & 7;
+                B = (dcb << 6) | dcb;
+                break;
+            }
+            case 5: {
+                C = 11;
+                const uint edcb = (bitval >> 1) & 0xF;
+                B = (edcb << 5) | (edcb >> 2);
+                break;
+            }
+            case 6: {
+                C = 5;
+                const uint fedcb = (bitval >> 1) & 0x1F;
+                B = (fedcb << 4) | (fedcb >> 4);
+                break;
+            }
+        }
+    } else { // QUINT
+        switch (bitlen) {
+            case 1:
+            C = 113;
+            break;
+            case 2: {
+                C = 54;
+                const uint b = (bitval >> 1) & 1;
+                B = (b << 8) | (b << 3) | (b << 2);
+                break;
+            }
+            case 3: {
+                C = 26;
+                const uint cb = (bitval >> 1) & 3;
+                B = (cb << 7) | (cb << 1) | (cb >> 1);
+                break;
+            }
+            case 4: {
+                C = 13;
+                const uint dcb = (bitval >> 1) & 7;
+                B = (dcb << 6) | (dcb >> 1);
+                break;
+            }
+            case 5: {
+                C = 6;
+                const uint edcb = (bitval >> 1) & 0xF;
+                B = (edcb << 5) | (edcb >> 3);
+                break;
+            }
+        }
+    }
+
+    uint T = (D * C) + B;
+    T ^= A;
+    T = (A & 0x80) | (T >> 2);
+    color_values_direct[++color_out_index] = T;
+}
+
 
 
 void ResultEmplaceBack(EncodingData val) {
+    if (write_color_values) {
+        if (color_out_index >= color_num_values) {
+            // avoid decoding more than needed by this phase
+            result_limit_reached = true;
+            return;
+        }
+        EmitColorValue(val);
+        return;
+    }
+
     if (result_index >= result_vector_max_index) {
         // Alert callers to avoid decoding more than needed by this phase
         result_limit_reached = true;
@@ -196,33 +303,36 @@ uint Hash52(uint p) {
     p ^= p >> 17;
     return p;
 }
+struct PartitionTable {
+    uint s1, s2, s3, s4, s5, s6, s7, s8;
+    uint rnum;
+    bool small_block;
+};
 
-uint Select2DPartition(uint seed, uint x, uint y, uint partition_count) {
-    if ((block_dims.y * block_dims.x) < 32) {
-        x <<= 1;
-        y <<= 1;
-    }
+PartitionTable GetPartitionTable(uint seed, uint partition_count) {
+    PartitionTable pt;
+    pt.small_block = (block_dims.y * block_dims.x) < 32;
 
     seed += (partition_count - 1) * 1024;
+    uint rnum = Hash52(uint(seed));
+    pt.rnum = rnum;
 
-    const uint rnum = Hash52(uint(seed));
-    uint seed1 = uint(rnum & 0xF);
-    uint seed2 = uint((rnum >> 4) & 0xF);
-    uint seed3 = uint((rnum >> 8) & 0xF);
-    uint seed4 = uint((rnum >> 12) & 0xF);
-    uint seed5 = uint((rnum >> 16) & 0xF);
-    uint seed6 = uint((rnum >> 20) & 0xF);
-    uint seed7 = uint((rnum >> 24) & 0xF);
-    uint seed8 = uint((rnum >> 28) & 0xF);
-
-    seed1 = (seed1 * seed1);
-    seed2 = (seed2 * seed2);
-    seed3 = (seed3 * seed3);
-    seed4 = (seed4 * seed4);
-    seed5 = (seed5 * seed5);
-    seed6 = (seed6 * seed6);
-    seed7 = (seed7 * seed7);
-    seed8 = (seed8 * seed8);
+    uint seed1 = (rnum & 0xF);
+    seed1 *= seed1;
+    uint seed2 = (rnum >> 4) & 0xF;
+    seed2 *= seed2;
+    uint seed3 = (rnum >> 8) & 0xF;
+    seed3 *= seed3;
+    uint seed4 = (rnum >> 12) & 0xF;
+    seed4 *= seed4;
+    uint seed5 = (rnum >> 16) & 0xF;
+    seed5 *= seed5;
+    uint seed6 = (rnum >> 20) & 0xF;
+    seed6 *= seed6;
+    uint seed7 = (rnum >> 24) & 0xF;
+    seed7 *= seed7;
+    uint seed8 = (rnum >> 28) & 0xF;
+    seed8 *= seed8;
 
     uint sh1, sh2;
     if ((seed & 1) > 0) {
@@ -232,31 +342,37 @@ uint Select2DPartition(uint seed, uint x, uint y, uint partition_count) {
         sh1 = (partition_count == 3) ? 6 : 5;
         sh2 = (seed & 2) > 0 ? 4 : 5;
     }
-    seed1 >>= sh1;
-    seed2 >>= sh2;
-    seed3 >>= sh1;
-    seed4 >>= sh2;
-    seed5 >>= sh1;
-    seed6 >>= sh2;
-    seed7 >>= sh1;
-    seed8 >>= sh2;
 
-    uint a = seed1 * x + seed2 * y + (rnum >> 14);
-    uint b = seed3 * x + seed4 * y + (rnum >> 10);
-    uint c = seed5 * x + seed6 * y + (rnum >> 6);
-    uint d = seed7 * x + seed8 * y + (rnum >> 2);
+    pt.s1 = seed1 >> sh1;
+    pt.s2 = seed2 >> sh2;
+    pt.s3 = seed3 >> sh1;
+    pt.s4 = seed4 >> sh2;
+    pt.s5 = seed5 >> sh1;
+    pt.s6 = seed6 >> sh2;
+    pt.s7 = seed7 >> sh1;
+    pt.s8 = seed8 >> sh2;
+
+    return pt;
+    }
+
+uint SelectPartition(PartitionTable pt, uint x, uint y, uint partition_count) {
+    if (pt.small_block) {
+        x <<= 1;
+        y <<= 1;
+    }
+
+    uint a = pt.s1 * x + pt.s2 * y + (pt.rnum >> 14);
+    uint b = pt.s3 * x + pt.s4 * y + (pt.rnum >> 10);
+    uint c = pt.s5 * x + pt.s6 * y + (pt.rnum >> 6);
+    uint d = pt.s7 * x + pt.s8 * y + (pt.rnum >> 2);
 
     a &= 0x3F;
     b &= 0x3F;
     c &= 0x3F;
     d &= 0x3F;
 
-    if (partition_count < 4) {
-        d = 0;
-    }
-    if (partition_count < 3) {
-        c = 0;
-    }
+    if (partition_count < 4) d = 0;
+    if (partition_count < 3) c = 0;
 
     if (a >= b && a >= c && a >= d) {
         return 0;
@@ -457,7 +573,7 @@ void DecodeIntegerSequence(uint max_range, uint num_values) {
     }
 }
 
-void DecodeColorValues(uvec4 modes, uint num_partitions, uint color_data_bits, out uint color_values[32]) {
+void DecodeColorValues(uvec4 modes, uint num_partitions, uint color_data_bits) {
     uint num_values = 0;
     for (uint i = 0; i < num_partitions; i++) {
         num_values += ((modes[i] >> 2) + 1) << 1;
@@ -471,104 +587,21 @@ void DecodeColorValues(uvec4 modes, uint num_partitions, uint color_data_bits, o
             break;
         }
     }
-    DecodeIntegerSequence(range - 1, num_values);
-    uint out_index = 0;
-    for (int itr = 0; itr < result_index; ++itr) {
-        if (out_index >= num_values) {
-            break;
-        }
-        const EncodingData val = GetEncodingFromVector(itr);
-        const uint encoding = Encoding(val);
-        const uint bitlen = NumBits(val);
-        const uint bitval = BitValue(val);
-        uint A = 0, B = 0, C = 0, D = 0;
-        A = ReplicateBitTo9((bitval & 1));
-        switch (encoding) {
-        case JUST_BITS:
-            color_values[++out_index] = FastReplicateTo8(bitval, bitlen);
-            break;
-        case TRIT: {
-            D = QuintTritValue(val);
-            switch (bitlen) {
-            case 1:
-                C = 204;
-                break;
-            case 2: {
-                C = 93;
-                const uint b = (bitval >> 1) & 1;
-                B = (b << 8) | (b << 4) | (b << 2) | (b << 1);
-                break;
-            }
-            case 3: {
-                C = 44;
-                const uint cb = (bitval >> 1) & 3;
-                B = (cb << 7) | (cb << 2) | cb;
-                break;
-            }
-            case 4: {
-                C = 22;
-                const uint dcb = (bitval >> 1) & 7;
-                B = (dcb << 6) | dcb;
-                break;
-            }
-            case 5: {
-                C = 11;
-                const uint edcb = (bitval >> 1) & 0xF;
-                B = (edcb << 5) | (edcb >> 2);
-                break;
-            }
-            case 6: {
-                C = 5;
-                const uint fedcb = (bitval >> 1) & 0x1F;
-                B = (fedcb << 4) | (fedcb >> 4);
-                break;
-            }
-            }
-            break;
-        }
-        case QUINT: {
-            D = QuintTritValue(val);
-            switch (bitlen) {
-            case 1:
-                C = 113;
-                break;
-            case 2: {
-                C = 54;
-                const uint b = (bitval >> 1) & 1;
-                B = (b << 8) | (b << 3) | (b << 2);
-                break;
-            }
-            case 3: {
-                C = 26;
-                const uint cb = (bitval >> 1) & 3;
-                B = (cb << 7) | (cb << 1) | (cb >> 1);
-                break;
-            }
-            case 4: {
-                C = 13;
-                const uint dcb = (bitval >> 1) & 7;
-                B = (dcb << 6) | (dcb >> 1);
-                break;
-            }
-            case 5: {
-                C = 6;
-                const uint edcb = (bitval >> 1) & 0xF;
-                B = (edcb << 5) | (edcb >> 3);
-                break;
-            }
-            }
-            break;
-        }
-        }
-        if (encoding != JUST_BITS) {
-            uint T = (D * C) + B;
-            T ^= A;
-            T = (A & 0x80) | (T >> 2);
-            color_values[++out_index] = T;
-        }
+    // Decode directly into color_values_direct[]
+    write_color_values = true;
+    color_out_index = 0;
+    color_num_values = num_values;
+    for (uint i = 0; i < 32; ++i) {
+        color_values_direct[i] = 0;
     }
+
+    DecodeIntegerSequence(range - 1, num_values);
+
+    write_color_values = false;
 }
 
+
+
 ivec2 BitTransferSigned(int a, int b) {
     ivec2 transferred;
     transferred.y = b >> 1;
@@ -730,7 +763,7 @@ uint UnquantizeTexelWeight(EncodingData val) {
     uint encoding = Encoding(val), bitlen = NumBits(val), bitval = BitValue(val);
     if (encoding == JUST_BITS) {
         return (bitlen >= 1 && bitlen <= 5)
-            ? uint(floor(0.5f + float(bitval) * 64.0f / float((1 << bitlen) - 1)))
+            ? ((bitval * 64) + ((1 << bitlen) - 1) / 2) / ((1 << bitlen) - 1)
             : FastReplicateTo6(bitval, bitlen);
     } else if (encoding == TRIT || encoding == QUINT) {
         uint B = 0, C = 0, D = 0;
@@ -1069,13 +1102,12 @@ void DecompressBlock(ivec3 coord) {
     uvec4 endpoints0[4];
     uvec4 endpoints1[4];
     {
-        // This decode phase should at most push 32 elements into the vector
-        result_vector_max_index = 32;
-        uint color_values[32];
+        // Decode directly into color_values_direct[] (no intermediate result_vector storage)
+        result_limit_reached = false;
         uint colvals_index = 0;
-        DecodeColorValues(color_endpoint_mode, num_partitions, color_data_bits, color_values);
+        DecodeColorValues(color_endpoint_mode, num_partitions, color_data_bits);
         for (uint i = 0; i < num_partitions; i++) {
-            ComputeEndpoints(endpoints0[i], endpoints1[i], color_endpoint_mode[i], color_values,
+            ComputeEndpoints(endpoints0[i], endpoints1[i], color_endpoint_mode[i], color_values_direct,
                              colvals_index);
         }
     }
@@ -1106,11 +1138,15 @@ void DecompressBlock(ivec3 coord) {
     DecodeIntegerSequence(max_weight, GetNumWeightValues(size_params, dual_plane));
 
     UnquantizeTexelWeights(size_params, dual_plane);
+    PartitionTable pt;
+    if (num_partitions > 1) {
+        pt = GetPartitionTable(partition_index, num_partitions);
+    }
     for (uint j = 0; j < block_dims.y; j++) {
         for (uint i = 0; i < block_dims.x; i++) {
             uint local_partition = 0;
             if (num_partitions > 1) {
-                local_partition = Select2DPartition(partition_index, i, j, num_partitions);
+                local_partition = SelectPartition(pt, i, j, num_partitions);
             }
             const uvec4 C0 = ReplicateByteTo16(endpoints0[local_partition]);
             const uvec4 C1 = ReplicateByteTo16(endpoints1[local_partition]);