A smart list only runs when you click Leads or when you call it from a Campaign/Report.
So you can archive it with no impact to the system.
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Archiving the lists will prevent them from appearing in search results, but to Josh's point, as far as overall system performance goes you won't see a boost.
Archiving old programs and deactivating unused trigger campaigns will however help with performance. For some other tips I find this a helpful read: