That sounds like my dosage but no dizziness. Last year I was still on a tennis court and I use a treadmill at home without an issue. Balance has changed somewhat but dizziness is not a problem. And this is my 9th year. Good luck my fellow traveler.
Keep moving.

Did your neurologists suggest such a large dosage.It doesn't slow down PD just combats symptoms but meds can produce similar symptoms

Do you take Entacapone with your Sinemet?