P2P is doing a lot of database lookups

[xgreenx]

When we request transactions for the block, each transaction requires a separate lookup, which is very expensive, considering that transactions are randomly distributed throughout the database(because of randomness of TxId).

[Voxelot]

Without changing the structure of the db to store full blocks instead of compact blocks, the most practical improvement with minimal changes would be to change this to a multi-get operation.

[rymnc]

Taking this up :)

[rymnc]

This is going to be partially solved with the caching layer in #2352