What causes memory fragmentation in .NET

Question

I am using Red Gates ANTS memory profiler to debug a memory leak. It keeps warning me that:

Memory Fragmentation may be causing .NET to reserver too

Answer 1

The GC heap treats large object allocations differently. It doesn't compact them, but instead just combines adjacent free blocks (like a traditional unmanaged memory store).

More info here: http://msdn.microsoft.com/en-us/magazine/cc534993.aspx

So the best strategy with very large objects is to allocate them once and then hold on to them and reuse them.