Most commonly traditional bows are tested at 28" AMO draw length using 9-10 GPP. High tech gear is based on a 30" draw length at IBO weight minimum of 5 gpp.
There are a lot of factors that determine the actual speed of an arrow coming out of a bow.
There is a large difference between measuring the "Bows effeicency" and the "Arrow velocity" as well as practical applications for hunting vs target shooting.... 3D competition vs shooting dots at 20 yards.... and field archery.
A bowyer can build a hot rod bow out of ultra light materials just using fiberglass and wood that would astound you with the chronograph numbers. the same thing can be accomplished using composites like carbon and foam cores.
But.... what the hunters as well as 3D competitors are looking for is the perfect mixture between high speed flat trajectory, good limb stability that keeps those limbs tracking consistently the same, and a smooth consistent draw cycle with the east amount of vibration. They also want durability and longevity... that's a lot to ask from mortal bowyer's. but it can be done.
The sound of the bow is very important to hunters too. using the right combination of string and tuning along with silences can adjust that on most bows.
The most common misconception regarding a bows efficiency and relating that to arrow speed, is the generalization and classification of different bow designs such as "ELB" "Hill Style" "Recurve" and "R/D long bows".
That would be the same as comparing cars to trucks, and motocross to street bikes in motorcycles.
It doesn't matter how long the car or truck is... it's what the thing is weighs, and what's under the hood, the gear ratio, and traction that gives you a 10 second quarter.
With a bow you are storing energy in the limbs and transferring that energy to the arrow shaft. the "Bows" efficiency is measured by calculating how much of that stored energy transfers to the arrow shaft.... typically the heavier the shaft, the more effeicent the "Bow" becomes.... not to be confused with the "Arrow efficiency"
Getting back to the thread topic "Pure speed" ... This is accomplished by balancing the mass weight of the limb itself to the draw weight, taking into consideration the mass weight of the arrow shaft being used. The length of the bow or the limbs themselves is not nearly as important as "the amount of working limb that is actually storing the energy." and having enough preload, or string tension at brace to stop the forward motion of the limb clean and transfer the energy to the shaft.
There are many different ways to accomplish this that i won't go into in detail. The short version is balancing all the mass weight of the working limb to actual draw weight, and shifting the location of that area where the limb bends to minimize forward motion, with enough preload to stop the limbs dead...... clear as mud, right?