Thanks for your reply.
I tried a delay, but unfortunately it only improved the time taken by 2-3 ms.
The data sheet doesn't say much, apart from that it can use 100k/s or 400k/s.
By 'change the algorithm' do you mean change the LCD library? I wouldn't know where to begin with that.
For now I shall concentrate on writing code that only updates values, which will save the time taken printing the units after each value on every loop.