Parallelize block validation operations

Currently, block validation operations in the engine tree execute sequentially. These operations are independent and can be parallelized for performance improvements.

Current implementation

https://github.com/paradigmxyz/reth/blob/main/crates/engine/tree/src/tree/payload_validator.rs#L271-L312

The handle_execution_error method performs sequential validation:

1. First calls validate_block_inner
2. Then calls validate_header_against_parent

Other Areas to look at:

Proposed implementation

Execute both validation operations in parallel using rayon::join:

let (block_validation, parent_validation) = rayon::join(
    || self.validate_block_inner(&block),
    || self.consensus.validate_header_against_parent(block.sealed_header(), parent_block)
);

• we can possibly parallelise validate_block_inner as well -

  reth/crates/engine/tree/src/tree/payload_validator.rs

  Line 708 in e276480

  fn validate_block_inner(&self, block: &RecoveredBlock<N::Block>) -> Result<(), ConsensusError> {

Other parallelization opportunities

1. Transaction signature recovery - Recover signatures for all transactions in a block in parallel
2. Multiple block validation - When validating multiple blocks in a batch, validate them in parallel
3. State prefetching - Prefetch state data in parallel while executing transactions (already partially implemented in prewarm.rs)
4. Consensus checks - Parallelize independent consensus validation checks within validate_block_inner

Concerns / Thoughts

The question tho is whether there’s a bigger opportunity to eliminate and simplify instead of optimising? and whether the overhead > parallelisation