diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -672,7 +672,7 @@
                  #include <byteswap.h>
                  #endif])
 
-AC_CHECK_DECLS([__builtin_clz, __builtin_clzl, __builtin_clzll])
+AC_CHECK_DECLS([__builtin_clz, __builtin_clzl, __builtin_clzll, __builtin_popcount])
 
 dnl Check for mallopt(M_ARENA_MAX) (to set glibc arenas)
 AC_MSG_CHECKING(for mallopt M_ARENA_MAX)
diff --git a/src/avalanche.h b/src/avalanche.h
--- a/src/avalanche.h
+++ b/src/avalanche.h
@@ -55,24 +55,6 @@
     // score.
     uint16_t confidence;
 
-    /**
-     * Return the number of bits set in an integer value.
-     * TODO: There are compiler intrinsics to do that, but we'd need to get them
-     * detected so this will do for now.
-     */
-    static uint32_t countBits(uint32_t value) {
-        uint32_t count = 0;
-        while (value) {
-            // If the value is non zero, then at least one bit is set.
-            count++;
-
-            // Clear the rightmost bit set.
-            value &= (value - 1);
-        }
-
-        return count;
-    }
-
 public:
     VoteRecord(bool accepted) : votes(0xaaaa), confidence(accepted) {}
 
@@ -87,29 +69,7 @@
      * Register a new vote for an item and update confidence accordingly.
      * Returns true if the acceptance or finalization state changed.
      */
-    bool registerVote(bool vote) {
-        votes = (votes << 1) | vote;
-
-        auto bits = countBits(votes & 0xff);
-        bool yes = bits > 6;
-        bool no = bits < 2;
-        if (!yes && !no) {
-            // The vote is inconclusive.
-            return false;
-        }
-
-        if (isAccepted() == yes) {
-            // If the vote is in agreement with our internal status, increase
-            // confidence.
-            confidence += 2;
-            return getConfidence() == AVALANCHE_FINALIZATION_SCORE;
-        }
-
-        // The vote did not agree with our internal state, in that case, reset
-        // confidence.
-        confidence = yes;
-        return true;
-    }
+    bool registerVote(bool vote);
 };
 
 class AvalancheVote {
diff --git a/src/avalanche.cpp b/src/avalanche.cpp
--- a/src/avalanche.cpp
+++ b/src/avalanche.cpp
@@ -5,6 +5,7 @@
 #include "avalanche.h"
 
 #include "chain.h"
+#include "config/bitcoin-config.h"
 #include "netmessagemaker.h"
 #include "scheduler.h"
 #include "validation.h"
@@ -13,6 +14,47 @@
 
 #include <tuple>
 
+static uint32_t countBits(uint32_t v) {
+#if HAVE_DECL___BUILTIN_POPCOUNT
+    return __builtin_popcount(v);
+#else
+    /**
+     * This computes the number of bits set in each group of 8bits then uses a
+     * multiplication to sum all of them in the 8 most significant bits and
+     * return these.
+     * More detailed explaination can be found at
+     * https://www.playingwithpointers.com/blog/swar.html
+     */
+    v = v - ((v >> 1) & 0x55555555);
+    v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
+    return (((v + (v >> 4)) & 0xF0F0F0F) * 0x1010101) >> 24;
+#endif
+}
+
+bool VoteRecord::registerVote(bool vote) {
+    votes = (votes << 1) | vote;
+
+    auto bits = countBits(votes & 0xff);
+    bool yes = bits > 6;
+    bool no = bits < 2;
+    if (!yes && !no) {
+        // The vote is inconclusive.
+        return false;
+    }
+
+    if (isAccepted() == yes) {
+        // If the vote is in agreement with our internal status, increase
+        // confidence.
+        confidence += 2;
+        return getConfidence() == AVALANCHE_FINALIZATION_SCORE;
+    }
+
+    // The vote did not agree with our internal state, in that case, reset
+    // confidence.
+    confidence = yes;
+    return true;
+}
+
 static bool IsWorthPolling(const CBlockIndex *pindex) {
     AssertLockHeld(cs_main);
 
diff --git a/src/config/CMakeLists.txt b/src/config/CMakeLists.txt
--- a/src/config/CMakeLists.txt
+++ b/src/config/CMakeLists.txt
@@ -110,6 +110,7 @@
 check_builtin_exist(__builtin_clz HAVE_DECL___BUILTIN_CLZ)
 check_builtin_exist(__builtin_clzl HAVE_DECL___BUILTIN_CLZL)
 check_builtin_exist(__builtin_clzll HAVE_DECL___BUILTIN_CLZLL)
+check_builtin_exist(__builtin_popcount HAVE_DECL___BUILTIN_POPCOUNT)
 
 # Memory management capabilities
 check_symbol_exists(M_ARENA_MAX "malloc.h" HAVE_MALLOPT_ARENA_MAX)
diff --git a/src/config/bitcoin-config.h.cmake.in b/src/config/bitcoin-config.h.cmake.in
--- a/src/config/bitcoin-config.h.cmake.in
+++ b/src/config/bitcoin-config.h.cmake.in
@@ -44,6 +44,7 @@
 #cmakedefine HAVE_DECL___BUILTIN_CLZ 1
 #cmakedefine HAVE_DECL___BUILTIN_CLZL 1
 #cmakedefine HAVE_DECL___BUILTIN_CLZLL 1
+#cmakedefine HAVE_DECL___BUILTIN_POPCOUNT 1
 
 #cmakedefine HAVE_MALLOPT_ARENA_MAX 1
 #cmakedefine HAVE_MALLOC_INFO 1