We need a bit more information: Where are you in the world, such as nearest large city? Is it mulched? What kind of trees? What type of irrigation system (for instance, is it overspray from the lawn or a dedicated drip system for specific plants in a bed, etc?) Can you add a photo of the plant? Have you had a soil test done?

As a general rule plants that have variegated leaves tend to grow a bit slower since the leaves have less chlorophyl for making food, but I don't have any direct experience with this plant and so don't know if it applies to this particular plant.

a pic also would help ....

im not sure that your words would translate into medium shade ... if its too dark ... and with less chlorophyll as babs suggests ... then vigor MIGHT be reduced ... and one description of that might be LEGGY ... stuff usually doesnt die in low light.. they just seem to not grow to expectation ... which sounds like where you are ...

4 years is surely long enough ... perhaps you need to move it????? .. which brings me back to maybe a pic will show us more ...

welcome to the forums ....

ken

Aucubas can take a lot of shade before becoming spindly, especially with adequate moisture, which isn't much to begin with.