diff --git a/arch/esp32/CPUUsageTracker.cpp b/arch/esp32/CPUUsageTracker.cpp
index 84441ea4..8cb7ff61 100644
--- a/arch/esp32/CPUUsageTracker.cpp
+++ b/arch/esp32/CPUUsageTracker.cpp
@@ -30,11 +30,10 @@ void CPUUsageTracker::_onSample() {
   const float sample = (total > 0) ? (float)db / (float)total : 0.0f;
 
   const uint8_t s8 = (uint8_t)(sample * 255.0f + 0.5f);
-  _sma_sum -= _sma_buf[_sma_idx];
+  const uint16_t last = _sma_buf[_sma_idx];
   _sma_buf[_sma_idx] = s8;
-  _sma_sum += s8;
+  _sma_sum = (_sma_sum - last) + s8;
   _sma_idx = (_sma_idx + 1) & (SMA_WINDOW - 1);
-  _sma_avg = (float)_sma_sum * (1.0f / (SMA_WINDOW * 255.0f));
 }
 
 void CPUUsageTracker::begin() {
diff --git a/arch/esp32/CPUUsageTracker.h b/arch/esp32/CPUUsageTracker.h
index eea394d0..d951c640 100644
--- a/arch/esp32/CPUUsageTracker.h
+++ b/arch/esp32/CPUUsageTracker.h
@@ -11,7 +11,9 @@ class CPUUsageTracker {
 public:
   void begin();
 
-  float getCore0Util() const { return _sma_avg; }
+  float getCore0Util() const {
+    return (float)_sma_sum * (1.0f / (SMA_WINDOW * 255.0f));
+  }
 
 private:
   static constexpr uint8_t SMA_WINDOW = 64;  // power of 2 — enables & mask
@@ -27,10 +29,9 @@ private:
   uint32_t _last_busy = 0;
 
   uint8_t  _sma_buf[SMA_WINDOW] = {};
-  uint16_t _sma_sum = 0;
   uint8_t  _sma_idx = 0;
 
-  volatile float _sma_avg = 0.0f;
+  volatile uint16_t _sma_sum = 0;
 
   esp_timer_handle_t _timer = nullptr;