Have anyone actually tested this?
Because increasing the Gap Limit to that amount would make Electrum unresponsive which is the very reason the OP was posted.
(at least in my multiple attempts to reproduce it)
I tried to test it:
wallet.change_gap_limit(50000)
After I clicked the Addresses tab, Electrum got stock. I killed it after eating 1 CPU core for 1.5 hours.