diff --git a/code/controllers/subsystem/SSinput.dm b/code/controllers/subsystem/SSinput.dm
index 4e4e27477fc..0ee76429738 100644
--- a/code/controllers/subsystem/SSinput.dm
+++ b/code/controllers/subsystem/SSinput.dm
@@ -22,6 +22,8 @@ SUBSYSTEM_DEF(input)
 	return "P: [length(processing)]"
 
 /datum/controller/subsystem/input/fire(resumed = FALSE)
+	// Sleeps in input handling are bad, because they can stall the entire subsystem indefinitely, breaking most movement. key_loop has SHOULD_NOT_SLEEP(TRUE), which helps, but it doesn't catch everything, so we also waitfor=FALSE here, as using INVOKE_ASYNC here is very unperformant.
+	set waitfor = FALSE
 	var/list/to_cull
 	for(var/client/C in processing)
 		if(processing[C] + AUTO_CULL_TIME < world.time)
diff --git a/code/modules/input/input.dm b/code/modules/input/input.dm
index 4600c311fb8..36aafd6a61b 100644
--- a/code/modules/input/input.dm
+++ b/code/modules/input/input.dm
@@ -5,6 +5,8 @@
 	return
 
 /datum/proc/key_loop(client/C)
+	// Sleeps in input handling are bad, because they can stall the entire subsystem indefinitely, breaking most movement. The subsystem sets waitfor=FALSE, which works around this, but we'd rather avoid the sleeps in the first place.
+	SHOULD_NOT_SLEEP(TRUE)
 	return
 
 /client/key_loop()