Is JQuery much slower than pure JavaScript ?

I wrote something with pure JavaScript at first and it worked fine, but the code is more complicated and difficult to maintain. So I have tried the JQuery library, and now the code is more elegant written, simple to read and understand.

BUT – I can feel the big change in performance. JQuery is slower in about half a second – second. I can feel the difference while using AJAX things that need to be updated.

Am I wrong?