For some reason, Dynamo running in Revit has EXTREMELY slow search performance - but only intermittently. I often have to wait several seconds for every letter i type in either the left-hand library search or right-click search. This makes Dynamo extremely painful to use. This has been true for at least the last year through various updates. Strangely, search in Dynamo standalone does not suffer from the same lag. Sometimes a simple search will take up to 30 seconds after typing, showing a spinny wheel until search results show up.
in the gif below you’ll see I can type an entire phrase before the dialog updates and returns results. This is not even close to how bad it can get: