To try to addresses these issues, I made my own implementation of the electrum server. It doesn't support UTXO (yet) but happily interacts with all the clients I've tested. It is heavily multithreaded, uses mongodb as a key value store and bitcoinj for block and transaction parsing.
You can hit a running instance at:
b.1209k.com:50002:s
or
b.1209k.com:50001:t
A synced node uses 347G of mongodb storage.
Here are the recent blocks imported, with number of transactions and import time.
These times are based on having mongodb on SSD.
The CPU is 8 core Intel(R) Xeon(R) CPU E5430 @ 2.66GHz
I'd be happy to help with anything you need to evaluate it.