The tag autocompletion could be improved in my opinion by putting a higher priority on matching at the beginning of the tag and at the beginning of word boundaries (as separated by a dash in tags).
The following example shows that the current behaviour is not optimal.
While the tag I was aiming for is the third proposed one, the first two are rather useless matches. They autocomplete inside words, which doesn't seem all that useful to me. I wouldn't start typing the middle of a word to find the tag.
I propose that the autocompletion should try to autocomplete at the start of a word if possible, matches inside words should have much lower priority than they have now.