If you mean Word, integration with Word for Mac can be relatively slow, so in a large document with many citations there might be delays while waiting for it to refresh citations in a document. In that case, disabling "Automatically update citations" in the plugin's Document Preferences window can help.
Zotero shouldn't have any effect on other apps. The only real exception would be if it's using a huge amount of memory, which you can check in Activity Monitor.
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Zotero shouldn't have any effect on other apps. The only real exception would be if it's using a huge amount of memory, which you can check in Activity Monitor.