Is it any performance downgrade when query separate db (by db link) on same physical server

I have simple question but i could find any information about it. I also run some tests but didn't get any results that i measurable. Let say i have same structure with same data on my db and second db. I have same query (second query is with db link). Will it be any performance downgrade when i will query different database by db link on same physical server? regards