Best Hardware for bcrypt

[ArnoNym]

After a while of playing around with differen vast.ai GPUs i dont think it is that easy anymore.
I would be glad if someone could help me answering this questions:

1. I have one instance with 4 times RTX 3080 wich is shown as 117.0 TFLOPS which runs my bcrypt hashes with 840 H/s = 3360.
   Another instance with 8 times RTX 2080ti is also shown as 117.0 TFLOPS but each instance is at 343 H/s = 2743 in Sum.
   For me it looks like it is not just a matter of "power" but also some other specific criteria. someone know more about this?
   
2. I run an instance of the rtx 4090 which was very powerful (7k H/s) for one hash and a big wordlist.
   But the same instance/hardware was just at 2k H/s when i used it with 90 hashes and the same wordlist.
   Why isnt hashcat just going through the hashes one by one if it would be almost 3 times faster if you look at the H/s?
   
3. And as far as i know bcrypt hashing has some specific hardware requirements (it needs alot of vram?). Thus i would ask the same question again: Is it better to use one powerful hardware that has alot of vram or is it more effizient to use alot of less powerful GPUs because they have the better "storage" ratio?
   
4. Does anyone have a similiar scenario or knowledge and can recommend hardware for this usecase (alot of hashes, wordlist attacks and a workfactor of 10 and 12)?
   What about the datacenter GPUs A100 and H100 are they better/more effizient than RTX GPUs?
   And for the RTXs are the higher generations more efficient than a bunch of lower generations?
   

Thanks for sharing your expierence and best regards