I can copy/paste 200 private keys into Electrum and it "pauses" for about 10-15 seconds... and then after clicking next it takes another 30 seconds to have a think while it creates the wallet and generates the address matching the private keys...
For the record, I have a Core i5-3570K, 8 GB RAM, Windows 10 64bit... OS and Electrum on an SSD...
I reckon I could probably crank through the addresses of ~20 seeds per hour without even really rushing... so you probably have 10+ hours worth of copy/paste to check all the seeds (assuming your "23" word seed generates a similar number of valid seeds as mine)
EDIT: In case anyone is interested, the (very) unpolished script is here:
https://github.com/HardCorePawn/btcMisc/usage:
generate_mnemonic_keys.py word1 word2 word3 ... wordN-1
Where N is a standard mnemonic length... ie. 12, 18, 24. So this means you should enter 11, 17 or 23 words!
NOTES:
- You NEED the wordlist directory and English.txt file
- Script will hunt for valid seeds, and once found, will generate 100 receive addresses/keys and 100 change addresses/keys and dump them into keys_XXX.txt file(s), one for each seed.
- Script is only looking for ONE missing word
- Script only looks for missing word from position2 to positionN-1 (ie. it does not look for a missing First or Last word)
- Script is only using BIP44 derivation path and only looks for Account 0 addresses/keys