The performance of `getLedgers` is too slow, even for smaller windows like `limit=10`

[marcelosalloum]

What problem does your feature solve?

When fetching ledger XDRs, applications expect the getLedgers call to be performant, so the catchup can occur in a timely manner.

Right now, calling getLedgers with limit=10 is taking almost 5 seconds, which is too slow.

What would you like to see?

I'd like to be able to execute this call with a larger window (> 10 ledgers) and stil get a good performance out of the RPC.

What alternatives are there?

N/A