I'm guessing the slowness is because your wallet is encrypted and the node will slow you don't because of the time it'll take to confirm your request there and I wouldn't suggest not keeping an encrypted file so a new wallet is probabky the best way to go...
These should be basic things for
experienced members who have been sharing tips for years when it comes to Electrum. Your suggestion that the wallet is slow because it is encrypted is actually completely missed.
Electrum always has a problem with a large number of addresses and a large number of transactions, which results in very slow synchronization and freezing when sending a transaction. If you already share tips, it wouldn’t be bad to read the Electrum FAQ.
This might happen if you are trying to spend a large number of transaction outputs (for example, if you have collected hundreds of donations from a Bitcoin faucet). When you send Bitcoins, Electrum looks for unspent coins that are in your wallet in order to create a new transaction. Unspent coins can have different values, much like physical coins and bills.
If this happens, you should consolidate your transaction inputs by sending smaller amounts of bitcoins to one of your wallet addresses; this would be the equivalent of exchanging a stack of nickels for a dollar bill.