diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -2547,6 +2547,10 @@
 directory updates in parallel on Unix-like systems, which greatly
 helps performance.
 
+``enabled``
+    Whether to enable workers code to be used.
+    (default: true)
+
 ``numcpus``
     Number of CPUs to use for parallel operations. A zero or
     negative value is treated as ``use the default``.
diff --git a/mercurial/worker.py b/mercurial/worker.py
--- a/mercurial/worker.py
+++ b/mercurial/worker.py
@@ -82,7 +82,8 @@
     args - arguments to split into chunks, to pass to individual
     workers
     '''
-    if worthwhile(ui, costperarg, len(args)):
+    enabled = ui.configbool('worker', 'enabled', True)
+    if enabled and worthwhile(ui, costperarg, len(args)):
         return _platformworker(ui, func, staticargs, args)
     return func(*staticargs + (args,))