It shouldn’t, as long as execution code is in c++ it will be ok !
I use c++ for 90% of my code, and for all small specific item i hook an even or so on special blueprint etc, and never seen perf hit from there.
On complex logic, blueprint can easily become spaghetti of nodes, hard to maintain / optimize
On as side note about blueprint performances,
Epic team added Blueprints Nativization, but it’s only when you cook i think