diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index 5b00b61ec0463..6bac48da4a4ac 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -88766,56 +88766,6 @@ mirror
 :
 always
 #
-ifdef
-XP_WIN
-#
-Controls
-whether
-or
-not
-TimerThread
-will
-automatically
-increase
-the
-Windows
-timer
-#
-resolution
-when
-appropriate
-conditions
-are
-met
-.
--
-name
-:
-timer
-.
-auto_increase_timer_resolution
-type
-:
-RelaxedAtomicBool
-#
-ifdef
-NIGHTLY_BUILD
-value
-:
-true
-#
-else
-value
-:
-false
-#
-endif
-mirror
-:
-always
-#
-endif
-#
 -
 -
 -
diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
index d72e959c0e9e4..dc4e19bfc4737 100644
--- a/xpcom/threads/TimerThread.cpp
+++ b/xpcom/threads/TimerThread.cpp
@@ -152,13 +152,6 @@ h
 #
 include
 "
-nsIPropertyBag2
-.
-h
-"
-#
-include
-"
 mozilla
 /
 Services
@@ -228,263 +221,6 @@ math
 .
 h
 >
-#
-ifdef
-XP_WIN
-/
-/
-Include
-Windows
-header
-required
-for
-enabling
-high
--
-precision
-timers
-.
-#
-include
-<
-windows
-.
-h
->
-#
-include
-<
-mmsystem
-.
-h
->
-static
-constexpr
-UINT
-kTimerPeriodHiRes
-=
-1
-;
-static
-constexpr
-UINT
-kTimerPeriodLowRes
-=
-16
-;
-/
-/
-Helper
-functions
-to
-determine
-what
-Windows
-timer
-resolution
-to
-target
-.
-static
-constexpr
-UINT
-GetDesiredTimerPeriod
-(
-const
-bool
-aOnBatteryPower
-const
-bool
-aLowProcessPriority
-)
-{
-const
-bool
-useLowResTimer
-=
-aOnBatteryPower
-|
-|
-aLowProcessPriority
-;
-return
-useLowResTimer
-?
-kTimerPeriodLowRes
-:
-kTimerPeriodHiRes
-;
-}
-static_assert
-(
-GetDesiredTimerPeriod
-(
-true
-false
-)
-=
-=
-kTimerPeriodLowRes
-)
-;
-static_assert
-(
-GetDesiredTimerPeriod
-(
-false
-true
-)
-=
-=
-kTimerPeriodLowRes
-)
-;
-static_assert
-(
-GetDesiredTimerPeriod
-(
-true
-true
-)
-=
-=
-kTimerPeriodLowRes
-)
-;
-static_assert
-(
-GetDesiredTimerPeriod
-(
-false
-false
-)
-=
-=
-kTimerPeriodHiRes
-)
-;
-UINT
-TimerThread
-:
-:
-ComputeDesiredTimerPeriod
-(
-)
-const
-{
-const
-bool
-lowPriorityProcess
-=
-mCachedPriority
-.
-load
-(
-std
-:
-:
-memory_order_relaxed
-)
-<
-hal
-:
-:
-PROCESS_PRIORITY_FOREGROUND
-;
-/
-/
-NOTE
-:
-Using
-short
--
-circuiting
-here
-to
-avoid
-call
-to
-GetSystemPowerStatus
-(
-)
-/
-/
-when
-we
-know
-that
-that
-result
-will
-not
-affect
-the
-final
-result
-.
-(
-As
-/
-/
-confirmed
-by
-the
-static_assert
-'
-s
-above
-onBatteryPower
-does
-not
-affect
-the
-/
-/
-result
-when
-the
-lowPriorityProcess
-is
-true
-.
-)
-SYSTEM_POWER_STATUS
-status
-;
-const
-bool
-onBatteryPower
-=
-!
-lowPriorityProcess
-&
-&
-GetSystemPowerStatus
-(
-&
-status
-)
-&
-&
-(
-status
-.
-ACLineStatus
-=
-=
-0
-)
-;
-return
-GetDesiredTimerPeriod
-(
-onBatteryPower
-lowPriorityProcess
-)
-;
-}
-#
-endif
 using
 namespace
 mozilla
@@ -1476,24 +1212,6 @@ resume_process_notification
 false
 )
 ;
-observerService
--
->
-AddObserver
-(
-mObserver
-"
-ipc
-:
-process
--
-priority
--
-changed
-"
-false
-)
-;
 }
 return
 NS_OK
@@ -5103,123 +4821,6 @@ SetLengthAndRetainStorage
 kMaxQueuedTimerFired
 )
 ;
-#
-ifdef
-XP_WIN
-/
-/
-kTimerPeriodEvalIntervalSec
-is
-the
-minimum
-amount
-of
-time
-that
-must
-pass
-/
-/
-before
-we
-will
-consider
-changing
-the
-timer
-period
-again
-.
-static
-constexpr
-float
-kTimerPeriodEvalIntervalSec
-=
-2
-.
-0f
-;
-const
-TimeDuration
-timerPeriodEvalInterval
-=
-TimeDuration
-:
-:
-FromSeconds
-(
-kTimerPeriodEvalIntervalSec
-)
-;
-TimeStamp
-nextTimerPeriodEval
-=
-TimeStamp
-:
-:
-Now
-(
-)
-+
-timerPeriodEvalInterval
-;
-/
-/
-If
-this
-is
-false
-we
-will
-perform
-all
-of
-the
-logic
-but
-will
-stop
-short
-of
-/
-/
-actually
-changing
-the
-timer
-period
-.
-const
-bool
-adjustTimerPeriod
-=
-StaticPrefs
-:
-:
-timer_auto_increase_timer_resolution
-(
-)
-;
-UINT
-lastTimePeriodSet
-=
-ComputeDesiredTimerPeriod
-(
-)
-;
-if
-(
-adjustTimerPeriod
-)
-{
-timeBeginPeriod
-(
-lastTimePeriodSet
-)
-;
-}
-#
-endif
 uint64_t
 timersFiredThisWakeup
 =
@@ -5344,63 +4945,6 @@ Now
 )
 ;
 #
-ifdef
-XP_WIN
-if
-(
-now
->
-=
-nextTimerPeriodEval
-)
-{
-const
-UINT
-newTimePeriod
-=
-ComputeDesiredTimerPeriod
-(
-)
-;
-if
-(
-newTimePeriod
-!
-=
-lastTimePeriodSet
-)
-{
-if
-(
-adjustTimerPeriod
-)
-{
-timeEndPeriod
-(
-lastTimePeriodSet
-)
-;
-timeBeginPeriod
-(
-newTimePeriod
-)
-;
-}
-lastTimePeriodSet
-=
-newTimePeriod
-;
-}
-nextTimerPeriodEval
-=
-now
-+
-timerPeriodEvalInterval
-;
-}
-#
-endif
-#
 if
 TIMER_THREAD_STATISTICS
 if
@@ -6617,42 +6161,6 @@ queuedTimersFiredPerWakeup
 )
 ;
 }
-#
-ifdef
-XP_WIN
-/
-/
-About
-to
-shut
-down
--
-let
-'
-s
-finish
-off
-the
-last
-time
-period
-that
-we
-set
-.
-if
-(
-adjustTimerPeriod
-)
-{
-timeEndPeriod
-(
-lastTimePeriodSet
-)
-;
-}
-#
-endif
 return
 NS_OK
 ;
@@ -9229,7 +8737,11 @@ Observe
 (
 nsISupports
 *
+/
+*
 aSubject
+*
+/
 const
 char
 *
@@ -9237,99 +8749,15 @@ aTopic
 const
 char16_t
 *
+/
+*
 aData
+*
+/
 )
 {
 if
 (
-strcmp
-(
-aTopic
-"
-ipc
-:
-process
--
-priority
--
-changed
-"
-)
-=
-=
-0
-)
-{
-nsCOMPtr
-<
-nsIPropertyBag2
->
-props
-=
-do_QueryInterface
-(
-aSubject
-)
-;
-MOZ_ASSERT
-(
-props
-!
-=
-nullptr
-)
-;
-int32_t
-priority
-=
-static_cast
-<
-int32_t
->
-(
-hal
-:
-:
-PROCESS_PRIORITY_UNKNOWN
-)
-;
-props
--
->
-GetPropertyAsInt32
-(
-u
-"
-priority
-"
-_ns
-&
-priority
-)
-;
-mCachedPriority
-.
-store
-(
-static_cast
-<
-hal
-:
-:
-ProcessPriority
->
-(
-priority
-)
-std
-:
-:
-memory_order_relaxed
-)
-;
-}
-if
-(
 StaticPrefs
 :
 :
diff --git a/xpcom/threads/TimerThread.h b/xpcom/threads/TimerThread.h
index 4c9fe67ca4f9a..dcc1f1a970d6f 100644
--- a/xpcom/threads/TimerThread.h
+++ b/xpcom/threads/TimerThread.h
@@ -176,15 +176,6 @@ include
 "
 mozilla
 /
-HalTypes
-.
-h
-"
-#
-include
-"
-mozilla
-/
 Monitor
 .
 h
@@ -528,103 +519,6 @@ MOZ_REQUIRES
 mMonitor
 )
 ;
-/
-/
-Using
-atomic
-because
-this
-value
-is
-written
-to
-in
-one
-place
-and
-read
-from
-/
-/
-in
-another
-and
-those
-two
-locations
-are
-likely
-to
-be
-executed
-from
-separate
-/
-/
-threads
-.
-Reads
-/
-writes
-to
-an
-aligned
-value
-this
-size
-should
-be
-atomic
-even
-/
-/
-without
-using
-std
-:
-:
-atomic
-but
-doing
-this
-explicitly
-provides
-a
-good
-/
-/
-reminder
-that
-this
-is
-accessed
-from
-multiple
-threads
-.
-std
-:
-:
-atomic
-<
-mozilla
-:
-:
-hal
-:
-:
-ProcessPriority
->
-mCachedPriority
-=
-mozilla
-:
-:
-hal
-:
-:
-PROCESS_PRIORITY_UNKNOWN
-;
 nsCOMPtr
 <
 nsIThread
@@ -1289,17 +1183,6 @@ const
 ;
 #
 ifdef
-XP_WIN
-UINT
-ComputeDesiredTimerPeriod
-(
-)
-const
-;
-#
-endif
-#
-ifdef
 DEBUG
 /
 /