How does driver priority work with regards to variables that are actually elements of a single structure in the PLC?

We're using the Logix_ODVA driver, and virtually all of our variables are structured under a single tag.

i.e.:

BaseTag.Group1.SubGroup1.VarName1

BaseTag.Group1.SubGroup2.VarName1

BaseTag.Group2.SubGroup1.VarName1

BaseTag.Group2.SubGroup1.VarName2

BaseTag.Group2.SubGroup1.VarName3

...

etc.

Currently there are about 3000 variables (and growing), and all individual variables are separately defined in Zenon (as a collection of BOOLS, DINTS, and REALS), but are actually a single UDT in the Rockwell PLC.

I'm trying to improve communication performance. I've disabled the Global update time and have configured 4 priority levels and assigned them to variables according to usage. It's hard to get a good measurement of response time, but so far it doesn't feel like I'm making any significant progress.

Is the fact that the driver addresses all the variables via a single Logix tag preventing me from taking advantage of driver priorities?