Resizable bar appears to be a PCIe enhancement that speeds up frequent small data transfers between CPU & GPU,
not typically an issue with GPU mining. It might theoretically help reduce the degradation of Eth zombie mode
on 4GB GPUs, if there are any compatible GPUs with only 4 GB.
It also requires a compatible CPU & motherboard.
Resizable BAR only works with GeForce RTX 30-series graphics cards. This series has a minimum memory capacity of 8 GB.
Miner developers are trying to increase performance for the latest graphics cards.
So far, only the Lol miner is extending the relevance of Ethereum mining for 4GB video cards.
And it will be relevant for 1-2 months.