If you did this (like the OP said), it would have to be done in a way such that the machines do larger amounts of work in each tick rather than updating twice as fast (Otherwise the increased computation would just slow tickrate more). That is, instead of having a macerator take energy/process ore twice in one tick (or twice as fast) you would have to have it consume twice as much energy but process 2 pieces of ore at once (obviously this would have to be consistent with how it currently operates in terms of LV/HV and energy usage/work done).
if (mctick % scale == 0)
updateMacerator(); // or whatever
Obviously the code is more complicated than this, but I'm assuming this is what you were suggesting. The problem would be that (assume IC updates every 10 MC ticks) when the scale goes from 10->5 the machine updates twice as fast which is good in that it removes any obvious slowdown BUT if IC is the reason for the slowdown it will just make the server slow more. (and if the scale goes down more, it will increase lag more....etc etc)
A way to avoid this as I said before, in the case of the macerator at least, would be to process more ore at once while using a proportional amount of EU. The problem would (probably) be that the machine would have to ask for more EU effectively making it higher voltage. So, you would have to add a similar scaling in the energy net code, which would probably be very annoying. Furthermore you probably cant do this with all machines, the terraformer for example would have no benefit from this, since the computationally intense process it uses is manipulating blocks. (so unlike the macerator you cant just go use 2x energy -> take 2 ore from itemstack -> make 4 dust, you still have to modify two blocks or whatever).
Ok I admit I have little idea how the IC code works, but from a coding standpoint and what little I understand I assume the situation is similar, at the very least it would take a significant rewrite of code to implement this.
Edit: Haha, I have to admit I didn't read all of the OP, and just happened to pick terraformers as something that wouldn't benefit as well. Well my post is pretty redundant but I'll leave it here anyway.