Specter v2.0.1 is now so slow that I get an error when trying to look at the settings for the wallet.

**Describe the bug**
I have a long-term wallet with over 1000 change addresses. I updated from v1.13 to v2.0.1. It takes many minutes to first load the wallets when opening Specter Desktop. Much much longer than with v1.13. If I select settings after about 1 minute I get a server error that lists the exception as 'dictionary changed size during iteration'. I have had to revert to the 1.13 app image to use Specter Desktop

**To Reproduce**
Happens every time I try to look at settings of this heavily used wallet.

**Expected behavior**
It should list the settings.

**Screenshots**
none

**Desktop (please complete the following information):**
- intel NUC
- Where is your specter running: binary
- If you're running a binary, which OS: Ubuntu
- Browser n/a
- Specter Version 2.0.1

Reproduce the settings load on Ubuntu with Specter Desktop v2.0.1 and a wallet containing over 1000 change addresses, then trace the reported "dictionary changed size during iteration" server error. Done means wallet loading no longer takes several minutes and the wallet settings page opens without an error.

Written by the indexing model from the issue text.