--- a/js/src/vm/Stopwatch.cpp
+++ b/js/src/vm/Stopwatch.cpp
@@ -314,17 +314,18 @@ AutoStopwatch::exit()
         // `getCPU()`.  We hope that this will happen rarely
         // enough that the impact on our statistics will remain
         // limited.
         const cpuid_t cpuEnd = this->getCPU();
         if (isSameCPU(cpuStart_, cpuEnd)) {
             const uint64_t cyclesEnd = getCycles(runtime);
             cyclesDelta = cyclesEnd - cyclesStart_; // Always >= 0 by definition of `getCycles`.
         }
-#if WINVER >= 0x600
+// Temporary disable untested code path.
+#if 0 // WINVER >= 0x600
         updateTelemetry(cpuStart_, cpuEnd);
 #elif defined(__linux__)
         updateTelemetry(cpuStart_, cpuEnd);
 #endif // WINVER >= 0x600 || _linux__
     }
 
     uint64_t CPOWTimeDelta = 0;
     if (isMonitoringCPOW_ && runtime->performanceMonitoring.isMonitoringCPOW()) {
@@ -406,31 +407,33 @@ uint64_t
 AutoStopwatch::getCycles(JSRuntime* runtime) const
 {
     return runtime->performanceMonitoring.monotonicReadTimestampCounter();
 }
 
 cpuid_t inline
 AutoStopwatch::getCPU() const
 {
-#if defined(XP_WIN) && WINVER >= _WIN32_WINNT_VISTA
+// Temporary disable untested code path.
+#if 0 // defined(XP_WIN) && WINVER >= _WIN32_WINNT_VISTA
     PROCESSOR_NUMBER proc;
     GetCurrentProcessorNumberEx(&proc);
 
     cpuid_t result(proc.Group, proc.Number);
     return result;
 #else
     return {};
 #endif // defined(XP_WIN)
 }
 
 bool inline
 AutoStopwatch::isSameCPU(const cpuid_t& a, const cpuid_t& b) const
 {
-#if defined(XP_WIN)  && WINVER >= _WIN32_WINNT_VISTA
+// Temporary disable untested code path.
+#if 0 // defined(XP_WIN)  && WINVER >= _WIN32_WINNT_VISTA
     return a.group_ == b.group_ && a.number_ == b.number_;
 #else
     return true;
 #endif
 }
 
 PerformanceGroup::PerformanceGroup()
     : recentCycles_(0)

--- a/js/src/vm/Stopwatch.h
+++ b/js/src/vm/Stopwatch.h
@@ -294,17 +294,18 @@ struct PerformanceMonitoring {
 
     /**
      * The highest value of the timestamp counter encountered
      * during this iteration.
      */
     uint64_t highestTimestampCounter_;
 };
 
-#if WINVER >= 0x0600
+// Temporary disable untested code path.
+#if 0 // WINVER >= 0x0600
 struct cpuid_t {
     uint16_t group_;
     uint8_t number_;
     cpuid_t(uint16_t group, uint8_t number)
         : group_(group),
           number_(number)
     { }
     cpuid_t()