CPU is maxed out on preliminary sync via Nextcloud Bookmarks

### Which version of floccus are you using?

4.13.1

### Sync method

{"label"=>"Nextcloud Bookmarks"}

### Which browser are you using? In case you are using the Android App, specify the Android version please.

Firefox 100.00 (64-bit)

### Which version of Nextcloud Bookmarks are you using? (if relevant)

hosted (unsure)

### Which version of Nextcloud? (if relevant)

22.2.7

### What kind of WebDAV server are you using? (if relevant)

_No response_

### Describe the Bug

CPU usage is freezing the computer on preliminary sync.

Floccus is unresponsive.

### Expected Behavior

Preliminary Sync will not cause computer to freeze.

### To Reproduce

Begin syncing from Floccus in Firefox.

i5 cpu
8gb ram
SSD disk

### Debug log provided

- [ ] I have provided a debug log file