Why do you need it to be in a real time? Are you just looking for the most profitable coin to mine and want to right what is profitable this instant instead of in the last 5 mins? Mostly the profitability from coin to coin won't change in 5 minutes. Even if it did it wouldn't be worth the effort in switching.
Or do you need these stats to make some calculations? Basically if you want the true network hashrate then you need to add up all the pools total hashrate and you would get a close estimate. Its very difficult to get the global net hashrate just by looking at the stats in the bitcoin core commands (or similiar wallets for altcoins) because the hashrate there is just based on how long it took to find the blocks in the past few hours, its never fully accurate since there is variance and miners switch on and switch off.
The best source for real time data is a stratum connection to a pool or wallet. If you let the (yiimp) pool do the autoswitching
it's done in real time, before the API or web page is updated. The stratum data is always for the current block, it has
to be to be able to submit valid shares.
As far as calculations, there is much that can be calculated with data obtained through the stratum connection.
For an example see the output of the latest version of cpuminer-opt. I don't calculate the network hash rate
but it's a function of network difficulty so is possible.
But it's awkward because you only get data for one coin at a time.
