Bug: Receive page lags or hangs for large wallets

Opening a wallet with many subaddresses causes severe lag and impact usability.

To reproduce the issue, create a wallet with many addresses in monero-wallet-cli.  For example, using:
```
address mnew 1000
```
30+ times in monero-wallet-cli will create a wallet with 30,001 addresses (like a very active BTCPay wallet).  With this many addresses, the app will lag on a performant PC.