This is a misleading question; and perhaps the answer I should put forward to you is this: If Hitler, especially early war, let the Italians 'hinder' him, its primarily because he allowed them to. He allowed them to by committing troops to secondary theaters, inevitably expanding them despite their limited strategic value viz. winning the war. A but and a big one I would throw in here, however, is that in most theaters, the Italians were less of a hindrance then many would like you to believe.

Here's what you need to understand before I launch into my post: The Italians were fighting what they viewed as a parallel war in North Africa in 1940. The Germans decided for reasons of prestige to expand this theater of war and draw off German manpower in North Africa for arguably little purpose other than to bail the Italians out. Certainly the initially sparse W-Desert Force would've resumed occupational and defensive duties after smashing the Italian 10th Army; and where the Germans went, Churchill, eager to expand and keep the British in the ground war, was sure to follow. However, Fortress Europe was water-tight at this time; and the experience in Greece (which I will elaborate on) seems to have confirmed this. By putting German soldiers in a position to engage in ground combat with the British; Hitler did little but fulfill the wildest wishes of Churchill.

The "Parallel War" theory suggests that, prior to the arrival of the lead units of the 5.LeichteDivision, the war in North Africa was, as Mussolini would've hoped, a separate affair. It seems many historians believe that the small Western Desert force and the stretched Middle Eastern command would've remained content with expelling the Italians out of their North African colonies, and certainly in 1940 the British were in no position to contest Axis control of the Mediterranean. Indeed, German intervention in North Africa, as small as it was at first, was made for the wrong reasons. I would liken German intervention in North Africa to British intervention in Greece; too little men, ill-advised, and more so for prestige than sound strategy.

(Source: Rommel's North African Campaign 1940-42 by Greene, Jacke et. Massignani, Alessandro)

In recent years as well, the notion that Germany's intervention in Yugoslavia and Greece somehow fatally delayed Barbarossa by one month is also subject to scrutiny, and I would argue that the idea is misleading. The formations that were used in Yugoslavia were heading East so I'd hardly call it a diversion of forces. Finally, it did clear what could've been at the very least an annoyance and threat to the Rumanian oil fields. Further, even if it was a delay, it certainly wasn't a significant one. The invasion of Yugoslavia lasted no more than a week, and Greece was largely conquered by April 30th; effective resistance in Yugoslavia collapsed practically within 24 hours and the actual drain on manpower was near minimal. I quote:

Shortly before dawn on 6 April, the most devastating phase of the Balkan war began with the simultaneous invasion of [Yugoslavia] and Greece...several thousand died when [Belgrade] was pounded to rubble by relentless bombing, and Yugoslav army's communications system collapsed.

From Crete: The Battle and the Resistance by Antony Beevor