Hi @Harry N Nomikos ,
I would suggest you don't do so many custom settings in the same list. According to my investigation, there are no clear restrictions in the SPO list, however more custom settings will inevitably affect the performance in the list.
For list performance, common steps are like below, have a try:
1.Add indexes on columns.
2.Edit the view and apply filters. Make sure only a portion of items will get diplayed under the current view.
Reference:
Manage large lists and libraries
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