Memory Allocation/Deallocation Bottleneck?

Question

How much of a bottleneck is memory allocation/deallocation in typical real-world programs? Answers from any type of program where performance typically matters are welcome.

Answer 1

Others have covered C/C++ so I'll just add a little information on .NET.

In .NET heap allocation is generally really fast, as it it just a matter of just grabbing the memory in the generation zero part of the heap. Obviously this cannot go on forever, which is where garbage collection comes in. Garbage collection may affect the performance of your application significantly since user threads must be suspended during compaction of memory. The fewer full collects, the better.

There are various things you can do to affect the workload of the garbage collector in .NET. Generally if you have a lot of memory reference the garbage collector will have to do more work. E.g. by implementing a graph using an adjacency matrix instead of references between nodes the garbage collector will have to analyze fewer references.

Whether that is actually significant in your application or not depends on several factors and you should profile the application with actual data before turning to such optimizations.