Using per item locks inside a loop

I have a static method which is accessed by many threads at the same time. For thread-safety collection this method iterating over would not change is size (no add/no delete). Note that item is a Lazy object and I don't have access to Lazy constructor to use the thread-safe one (MEF do that):

private static readonly object _syncLock = new object();

// Now inside a static method

private static DoSomethingOnItem(string wanted)
{
   foreach (var item in items)
   {
      if (item.Metadata["Name"] = wanted)
      {
         lock (_syncLock)
            item.DoSomething();
      }
   }
}

Does it boost performance if I use and array of locks per item or many locks have much side-effect rather than performa开发者_开发技巧nce boosting ?

private static object[] _syncLocks;
// Code...
_syncLocks = new object[itemsCount]; // in a thread-safe manner

Then inside the loop use each item specific lock

Why not just lock on the item object, rather than create an array of locks?

I.e.

private static void DoSomethingOnItem(string wanted)
{
   foreach (var item in items)
   {
      if (item.name == wanted)
      {
         lock (item)
            item.DoSomething();
      }
   }
}