Specifically, I want to reduce the overall load on the HTTP origin servers. Looking at the performance of the servers, disk IO seems to be a significant bottleneck, so anythign that coudl reduce teh load on teh servers woudl help. The documentation on IOBufferSize was the only thing I coudl see, and there is no guidance on what the values actually mean. Certainally I cannot see why the value of 4096 is the default, as this woudl seem to be very low for any kind of video delivery.
I am not concerned so mush with live delay, but any advise on reducing CPU or memory usage is also of benefit.
Servers are running 4.5.2, mostly with teh default parameters. All content is encrypted using Flash Access, and jit.conf configuration for on-demand assets. Live is also Flash Access encrypted.
I think load on your server is not because of recording - its more to do with your subscribers. As more and more subscribers hit you there would be more load on your server - the way to spread this is to have network of Caching Servers in between and spread the load - so that each request does not hit the Origin server.