This is a a question about skill vs. innovation, and I say: no, there are other ways to achieve higher ways of innovation without shortening lifespan that much.
Long lived: the power of specialists
Of course, having a long life for a species does increase the time to become considered adult, but the average skill level and level of specialisation any of the members has is much higher than a relatively shortlived species.
Being that longlived, there is little pressure to procreate, which reduces population growth as a whole. Having a low growth rate with a high tech base leads to them training up specialists to a degree where only a handful of people is acting in any given area of technology. That has good and bad sides: while specialists are more likely to invent a fully novel thing from scratch (think about Einstein and his collegues), there are possibly much less applications for the daily life. Also, new ideas do need more time to take root in such an environment, as total turnovers in scientific areas usually are about half a generation.
Short lived = fast procreation: tiny steps of innovation
Being shortlived with an average of 40 with a very very rare record of 90 for high medival humans did press them to procreate early. This increased the population numbers even if facing famine, high death rates and war slowly. At some critical point in the high middle ages, this procreation cycle started to increase the population more rapidly because of tiny inventions that would lessen the death toll due to hunger - This was NOT a major breakthrough, human advancement is powered by series of tiny changes!
It was stuff like the iron plow instead of the wooden one. Which then was changed gradually to turn the surface. Being short lived did not press them to invent more, it pressed them to procreate more and thus increase the chance someone would invent something to better their items. These tiny steps were aided with as many of these many people were proficient with the same tools and thus there was a big chance that someone of this large group would have a good idea liketaking iron for a plow or turning over the field.
Indeed, in human history in the real world, major breaktrhoughs on their own are almost unheard of and those that are are famous. Penicillin is one of these, and it is the result of the power of specialists above. Most often somebody would just take old parts and recombinate them in a novel and innovative way, especially in industrial revolution.
Diesel knew well about steam engines and had experimented with fuels combusting explosively under some conditions. Combinding and redesigning parts of a steam engine, he made the diesel engine. Daimler combined a cart with an engine.
1. Increase fertility
Well, there are several ways to go for the techno elves. First, they could increase their population growth, increasing pressure and capacity for innovation. That is actually a fairly easy fix, if they are genetic engineers: just feed the people fertility meds.
With the higher population growth, they achieve several goals at once:
- they increase their workforce and have a larger pool of people to draw from for military.
- they increase the chance of a new idea cropping in the head of a being familiar with the right tool to improve
- they reduce the time for ideas taking root in the scientific environments, as the numbers of these increase - younger generations copy ideas of each other and thus tilt the scales in their favor somewhat.
2. Fastern up maturity
Being genetic engineers, it might be easily doable to reduce the time to reach maturity from 100 to like 50 by adding meds to the diet. Going more could become really harmful for their brain development. With 45 years of training, you still retain a highly specialized workforce with a high live span of possibly something close to where they started, maybe 400-500 to 1000, makign them a bit more longlived than dwarfs.
3. Not reduce own longlivity
Why should the species reduce the longlivity even more? The pressure for innovation is not impeding death by age for humans, it is impeding death by hunger or other humans, so they innovate at things to fence of dying of hunger or to kill other humans before they do. For humans, 2 things bring forward advancement: hunger and war. Being as longlived as elvens are, they likely found a way past hunger long ago and the typical elven picture isn't about war all the time. So... let's create both pressures for the Tech Elfs:
4. Create servant race
Instead of cutting down the own longlivity, the elves and dwarfs could start to make a somewhat smart and sturdy warrior caste that is fed by the population of their techno-kingdom for nothing else but their service as warriors. It might be the reason why there are Orks: they are the warrior extension of the Dwarven/Elven coalition, designed to be bigger, stronger and harder to take down than humans, smart enough to be a good tactican and use their weaponry and give feedback to the weapon designers in their ivory towers. They don't need to have a very long live, but they have to gain a culture that takes pride in warfare. Feeding them well for little but training will result in them being mostly ok with their lot as the shield & arm of society. Even giving their most valued veterans a position in the governing council will help to prevent rebellions of this specis that might reach maturity at 12 and might to expect only to reach 30-35 (ignoring war casualties).
With such an army that grows even faster than humans (add cloning orcs?), there would be increased pressure on ther scientists to innovate food production, tailor weapons especially for the orc regiments and overall innovate in logistics.