If you have a Eucalyptus tree, and it is not growing that fast, then there is probably something wrong with it. But in reality, 3' of growth in one season is rather pathetic as eucalypts go. First, in cultivation outside of Australia eucalypts are not tormented by grazing kangaroos, koalas, and all sorts of insect pests like they are in Australia, not to mention the challenges of having to grow in poor soil, and compete with grass and each other.
Eucalypts basically have it easy in cultivation, and take full advantage of it.
They are able to grow whenever they have access to water and a little warmth, regardless of what time of the year it is, unlike most other trees which do most or all of their growing in the spring and early summer and then stop. E. vernicosa probably grows even more slowly. E. pauciflora and its subspecies should grow about 3 - 5' per year, but there are a few dwarf forms of various snow gums that may grow 1' per year or less. To correct this, cover the area around the base of the trunk with newspaper to smother out the grass, and mulch it heavily with compost. The grass roots will eventually rot, and the compost will give the eucalyptus a boost.