Track round-start setup time (#2791)

Adds a debug log to track round-start setup time for diagnostic purposes.

code/controllers/subsystems/ticker.dm

@@ -363,6 +363,8 @@ var/datum/controller/subsystem/ticker/SSticker
 		SSjobs.ResetOccupations()
 		return 0
 
+	var/starttime = REALTIMEOFDAY
+
 	if(hide_mode)
 		world << "<B>The current game mode is - Secret!</B>"
 		if(runnable_modes.len)
@@ -402,6 +404,8 @@ var/datum/controller/subsystem/ticker/SSticker
 	run_callback_list(roundstart_callbacks)
 	roundstart_callbacks = null
 
+	log_debug("SSticker: Round-start setup took [(REALTIMEOFDAY - starttime)/10] seconds.")
+
 	return 1
 
 /datum/controller/subsystem/ticker/proc/run_callback_list(list/callbacklist)