Try changing LockImpl to not have a spin count to see how it affects performance.

base/synchronization/lock_impl_win.cc

Index: base/synchronization/lock_impl_win.cc
diff --git a/base/synchronization/lock_impl_win.cc b/base/synchronization/lock_impl_win.cc
index fbc1bdd464b01254fb4bef8a9e2f1053553d3a07..86febe911a99d9e69f743a2f4498d1cf96f1b37f 100644
--- a/base/synchronization/lock_impl_win.cc
+++ b/base/synchronization/lock_impl_win.cc
@@ -8,9 +8,7 @@ namespace base {
 namespace internal {
 
 LockImpl::LockImpl() {
-  // The second parameter is the spin count, for short-held locks it avoid the
-  // contending thread from going to sleep which helps performance greatly.
-  ::InitializeCriticalSectionAndSpinCount(&native_handle_, 2000);
+  ::InitializeCriticalSection(&native_handle_);
 }
 
 LockImpl::~LockImpl() {