OmnipotentVoid

Interestingly enough, the fact that everything constantly updates the multi block structure doesn't take that much power in FTD. This is because each MBS (multi block structure) has a central controller that basically checks how many functioning blocks are attached to it and calculates everything based on that.
In FTD ship size and entity count (all projectiles are entities) are the main cause of performance decrease. Also, calculations would be done server side, which means there would probably be plenty of processer power available, considering voxel based games usually have more problems with RAM rather than processor power.

What I mean by entities is literally bullet spam to the point of ludicrousness in FTD. I have made a capital ship with 8 CWIS systems firing 3000rpm. Plus 20 secondary batteries and 12 main battery guns, this results in roughly 25000 entities. Plus the 200000 blocks of the ship. This tanks my frame rate from (capped) 60fps to 15fps. The 12 engines (spread across multiple sections for redundancy and space efficiency) plus 45 multi block weapons systems and the multi block laser anti missile system totalling roughly 75000 blocks don't cause a notable performance loss.
This is because each system is built around a central (programming wise, not positioning wise) control block, witch calculates what the system does based on the attached blocks. The blocks themselves just check wether they are functioning (not destroyed, attached to the right thing, etc.) and if they are connected to a control block. This way, of the 75000 blocks in the MBSs, only 58 are doing any significantly taxing calculations. The rest are just doing health checks and attachment checks like all blocks on the craft. In FTB all of the blocks are doing taxing calculations. So you may only have 200 blocks of machines, but all of them are doing calculations, rather than the 58 on my 200000 block ship.

The biggest disappointment in space engineers was the fact that there was no actual engineering. Building in the game (to me) feels more like an exercise in esthetics, slapping on functional parts as necessary. The fact that the capabilities of a ship in space engineers is defined more by what and how many functional parts were on a ship, than the actual design is extremely disappointing.
In From the Depths, on the other hand, design has a meaning. In FTD most functional parts of a ship are multi block structures. The way these are built effect the performance of the ship drastically. This means compromises must be made. Summarized into a triangle, a design of any component must balance between size, power and efficiency.
For example: there is a very efficient 7x7x2n engine design (2n means it is tile able, but one tile must be 2 blocks thick) however, of the 98 blocks per tile, only 4 are the power generating cylinders. The rest increase power output per cylinder and efficiency, or are pipes and dead space. Thus I cannot use the design on small ships or ships that need a lot of power in a small space.
This gets a lot more complex for some systems, like the advanced projectile system.
So I would really like to see a multi block systems mechanic added to this game. It would significantly increase depth and variety, while being avoidable by those who do not want to go so in depth. It adds on to player interaction as well (pro/con list below).
 
Of course, some people are not interested in designing stuff. In FTD, you get around this by either copying someone's design or using prefabs, which are like blueprints that place parts of or even entire multi block assemblies. This way, if you don't want to spend a long time designing a system, you don't have to.
 
Also of note: the capabilities of a system don't have to depend solely on the design, just as you could have multiple/upgraded parts, components of a system could have upgraded or specialized version, that require certain resources, research or infrastructure to produce. This also adds cost/ effectiveness to the design considerations.
 
Single block components would also still be relevant. They should be cheaper (as the are prefabricated) and smaller, but less specialized and not a scalable. They would be used to quickly produce small, inexpensive objects (drone, turrets, mines, etc.).
 
Pros:
-more depth
-better customization
-more individual designs
-no optimal design/better specialization
-more balancing factores/more subtle balancing allows for better over all balance ( if done properly)
-adds an appealing side to design other than esthetics
-expands perfectly on the build your own universe idea
-avoidable if you're not interested
-adds another specialization possibility for players (engine designer, weapon designer, etc.)
-adds another trade good (blueprints, possibly the prefaced system)
-adds more weapon/system variety for all players, not only those who would use the system design mechanic
 
Cons:
-longer (but not steeper) learning curve (that can be avoided)
-takes longer/may be harde to balance
-may take more processing power (server side)
 
Note: I mainly imagine thes multi block structures for larger ships, not for something as smal as a fighter.