Paging is workload is generally dominated by random IO. In general paging will be much faster on an SSD than a spindle because random IO destroys throughput in

Paging is workload is generally dominated by random IO. In general paging will be much faster on an SSD than a spindle because random IO destroys throughput in MB/sec on a spindled disk. Memory is the new disk and in general what will kill you performance-wise between the Pro and the Air is the CPU cache. You're only going to notice the difference between 4 GB and 8 GB if your working set exceeds 4 GB. On 8GB I run Photoshop, XCode, Chrome, a couple VMs, and some other memory hungry processes, however, at any given time I'm generally only using a couple of those processes, eg. Chrome / Photoshop, or XCode / Photoshop, or Vim / VMs, or Vim / Chrome. It sometimes takes a few seconds for the VMs to start performing properly or XCode to become responsive but it's only when I switch tasks that I notice it. I'd recommend against switching to the Air for increased performance. If you really want to know what it's like with 4GB why not just take 4GB out of your Pro and see if you can live with it?