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RAM performance is the same for VMs and bare metal. And the ~1.5x performance difference between different grades of DRAM (e.g. 1333 vs. 1600 vs. 2133 MHz) is negligible compared to the massive cache-RAM and RAM-flash gaps.

And speaking of cache, lstopo (from the hwloc package) does work correctly under EC2.

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It may be the same in the sense that hypervisors don't explicitly limit it, but on a multicore host you're sharing memory bandwidth with the other guests, in the common(?) case when the host has more cores than a guest. You can also experience increased latency when there is access contention.

True, if you want full and predictable memory/cache performance you need to rent a full-machine VM (usually 8xlarge) or bare metal.

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