"Activating this will double your CpS for 1 hour, at a cost of 1 sugar lump. May be used only once per ascension."
It's tempting. Certainly it's not worth my using it while I still have fewer than 100 unspent sugar lumps. SF gives a windfall equal to one hour's production. Keeping that lump instead of spending it on SF gives an extra 1% CpS, so after 100 hours it gives more cookies than SF - and most of my runs last well over 100 hours.
Once I have 100 sugar lumps stored up, it MAY be worth it. The next best use of sugar lumps is to level up buildings, the best one being the one for which the increased production divided by the number of lumps required for levelling up is a maximum. Levelling up one building gives a boost of much less than 1% of CpS because it's only one building; moreover the number of lumps required is proportional to the current level, so the break-even point becomes several hundred hours, or maybe in the thousands. At my current advanced stage of the game, my runs are approaching the 1000-hour point, however earlier runs were much shorter, so Sugar Frenzy would be worth it.
The question then becomes: is there a point at which it's worth cutting runs short so as to increase the frequency with which Sugar frenzy can be invoked? Calculations pending.