slow...you may have a couple of problems. Firstly, when growing in containers there are some very important factors. 1. use a free draining potting mix (no moisture control stuff to create muck. 2. Make sure the container is large enough. 3. Watering regularly is critical. Also, persea mites can cause tan/silverfish spotting on the underside of leaves. They usually run along the vein line. You definitely have the soil moisture/watering issue.

Thanks fireduck - yes, it was in a smaller container before and would dry out all the time (bad bad mama) but I think the bigger container is helping, and I did use cactus/palm/citrus potting mix which is supposed to drain well.

However, the very tips of the newer leaves are still brown. The soil feels cool and moist under the mulch....hmmm...
I potted it up from a 12 to a 14 or so - my understanding is you should usually pot up gradually to larger sizes rather than going to a giant pot right away. I know avocado trees get huge....

the brown edges on those leaves will never re-green. No bigee. Keep it fed with low-dose fertilizer...and don't let it get root-bound.